Flash MCU
Workshop
Atmel Korea
Flash MCU
Workshop Goals
• Detailed Architecture Knowledge
• Hands on experience with the AVR Tools
– IAR Assembler and C-Compiler
– AVR Studio
– AVR Emulator
• Design your own AVR Beer Altimeter
Flash MCU
AVR Presentation
• Architecture
• Instruction set
• Peripherals
Flash MCU
Key Features
•
•
•
•
•
•
•
Highest Performance 8-Bit MCU
Real RISC Architecture
32 Registers, 2-Address Machine, Single Cycle Execution
Low Power
8 MB Direct Address Reach
Fast Context Switching
Efficient C Language Code Density
RISC Performance with CISC Code Density
Flash MCU
Breaking Traditions
Code Density
Traditional
CISC
Traditional
RISC
Speed
Flash MCU
AVR Architecture
An introduction to the MCU
Flash MCU
Block Diagram
Flash MCU
Register File
R0
R1
R2
R3
R26
R27
R28
R29
R30
R31
XL
XH
YL
YH
ZL
ZH
Register File
X Pointer
Y Pointer
Z Pointer
Flash MCU
Direct Register - ALU Connection
Register operations
take ONE clock pulse
on the EXTERNAL clock
input
Register File
ALU
Flash MCU
Execute 2 Instructions
1 2
PIC
1
HC05
1
‘C51
1
Done!
2
Done!
2
Done!
2
Done!
Flash MCU
A C-Code Example
The following example illustrates how
the AVR benefits in terms of:
Code Size
Throughput
Power Consumption
Flash MCU
A Small C Function
/* Return the maximum value of a table of 16 integers */
int max(int *array)
{
char a;
int maximum=-32768;
for (a=0;a<16;a++)
if (array[a]>maximum)
maximum=array[a];
return (maximum);
}
Flash MCU
AVR Assembly output
; 7.
for (a=0;a<16;a++)
LDI
R18,LOW(0)
LDI
R19,128
CLR
R22
LDD
LDD
CP
CPC
BRGE
?0001:
; 8.
; 9.
CPI
R22,LOW(16)
BRCC
?0000
{
if (array[a]>maximum)
MOV
R30,R22
CLR
R31
LSL
R30
ROL
R31
ADD
R30,R16
ADC
R31,R17
MOV
MOV
R20,Z+0
R21,Z+1
R18,R20
R19,R21
?0005
maximum=array[a];
R18,R20
R19,R21
INC
RJMP
R22
?0001
; 10.
?0005:
?0000:
; 11.
; 12.
; 13.
}
return (maximum);
MOV
R16,R18
MOV
R17,R19
}
RET
Code Size: 46 Bytes, Execution time: 335 cycles
Flash MCU
C51 Assembly Output
; FUNCTION _max (BEGIN)
;---- Variable 'array' assigned to Register 'R1/R2/R3' ---; SOURCE LINE # 4
; SOURCE LINE # 5
; SOURCE LINE # 7
MOV
maximum,#080H
MOV
maximum+01H,#00H
; SOURCE LINE # 9
;---- Variable 'a' assigned to Register 'R5' ---CLR
A
MOV
R5,A
?C0001:
; SOURCE LINE # 10
; SOURCE LINE # 11
MOV
A,R5
MOV
R7,A
RLC
A
SUBB
A,ACC
MOV
R6,A
MOV
A,R7
ADD
A,ACC
MOV
R7,A
MOV
A,R6
RLC
A
MOV
DPL,R7
MOV
DPH,A
LCALL
?C?ILDOPTR
MOV
R7,A
MOV
R6,B
SETB
C
SUBB
A,maximum+01H
MOV
A,maximum
XRL
A,#080H
MOV
R0,A
MOV
A,R6
XRL
A,#080H
SUBB
A,R0
JC
?C0003
; SOURCE LINE # 12
MOV
maximum,R6
MOV
maximum+01H,R7
; SOURCE LINE # 13
?C0003:
INC
R5
CJNE
R5,#010H,?C0001
?C0002:
; SOURCE LINE # 14
MOV
MOV
R6,maximum
R7,maximum+01H
; SOURCE LINE # 15
?C0005:
RET
; FUNCTION _max (END)
?C?ILDOPTR:
CJNE
R3,#0x01,0x195
MOV
A,0x82
ADD
A,R1
MOV
0x82,A
MOV
A,0x83
ADDC
A,R2
MOV
0x83,A
MOVX
A,@DPTR
MOV
OxF0,A
INC
DPTR
MOVX
A,@DPTR
RET
JNC
0x1A0
MOV
A,R1
ADD
A,0x82
MOV
R0,A
MOV
0xF0,@R0
INC
R0
MOV
A,@R0
RET
CJNE
R3,#0xFE,0xAD
MOV
A,R1
ADD
A,0X82
MOV
R0,A
MOV
A,@R0
MOV
0xF0,A
INC
R0
RET
MOV
A,0X83
ADD
A,R2
MOV
0X83,A
MOV
A,R1
MOVC
A,@A+DPTR
RET
Code Size: 112 Bytes, Execution time: 9384 cycles
Flash MCU
HC11 Assembly output
; 7.
for (a=0;a<16;a++)
TSX
LDD
#-32768
STD
1,X
CLR
0,X
?0001:
; 8.
; 9.
STD
5,X
INS
INS
CPD
BLE
STD
3,X
?0005
maximum=array[a];
3,X
TSX
INC
BRA
0,X
?0001
; 10.
LDAA
0,X
CMPA
#16
BHS
?0000
{
if (array[a]>maximum)
PSHY
TAB
CLRA
LSLD
TSX
ADDD
0,X
XGDX
LDD
0,X
TSX
?0005:
?0000:
; 11.
; 12.
; 13.
}
return (maximum);
LDD
1,X
}
PULX
PULX
INS
PULY
RTS
Code Size: 57 Bytes, Execution time: 5244 cycles
Flash MCU
PIC16C74 Assembly output
bcf
3,5
movwf ?a_maxnum& (0+127)
;MAX_MAIN.C: 4: char a;
;MAX_MAIN.C: 5: int maximum=-32768;
clrf
(?a_maxnum+2)& (0+127)
movlw
128
movwf
(?a_maxnum+3)& (0+127)
;MAX_MAIN.C: 7: for (a=0;a<16;a++)
clrf
(?a_maxnum+1)& (0+127)
l2
;MAX_MAIN.C: 8: {
;MAX_MAIN.C: 9: if (array[a]>maximum)
bcf
3,5
movf
(?a_maxnum+1)& (0+127),w
addwf (?a_maxnum+1)& (0+127),w
addwf
?a_maxnum& (0+127),w
movwf
4
movf
0,w
movwf
btemp
incf
4
movf
0,w
movwf
btemp+1
movf
(?a_maxnum+3)& (0+127),w
xorlw
128
movwf
btemp+2
movf
btemp+1,w
xorlw
128
subwf
btemp+2,w
btfss
3,2
goto
u15
movf
btemp,w
subwf
(?a_maxnum+2)& (0+127),w
u15
btfsc
3,0
goto
l5
;MAX_MAIN.C: 10: maximum=array[a];
bcf
3,5
movf
(?a_maxnum+1)& (0+127),w
addwf
(?a_maxnum+1)& (0+127),w
addwf
?a_maxnum& (0+127),w
movwf
4
movf
0,w
movwf
(?a_maxnum+2)& (0+127)
incf
4
movf
0,w
movwf
(?a_maxnum+3)& (0+127)
l5
;MAX_MAIN.C: 11: }
bcf
3,5
incf
(?a_maxnum+1)& (0+127)
movlw
16
subwf
(?a_maxnum+1)& (0+127),w
btfss
3,0
goto
l2
;MAX_MAIN.C: 12: return (maximum);
bcf
3,5
movf
(?a_maxnum+3)& (0+127),w
movwf btemp+1
movf
(?a_maxnum+2)& (0+127),w
movwf
btemp
return
Code Size: 87 Bytes, Execution time: 2492 cycles
Flash MCU
Some Conclusions on THIS Case
• The C51 would have to run at 224 MHz to match the 8
MHz AVR.
• The HC11 is quite code efficient, but delivers only one
16th of the processing power at more than twice the
current consumption
• The PIC is a fast microcontroller, but the AVR delivers
more than 3.5 times higher throughput per mW.
Flash MCU
What made the AVR do better?
• Excellent support for 16-bit arithmetic's. (Zero-Flag
Propagation on Compare)
• A lot of registers which eliminate move to and from
SRAM
• Single Cycle execution
Flash MCU
AVR Microcontrollers
Which AVR Devices are available today?
Flash MCU
Current AVR Product Line
‘S1200
FAMILY
‘S2323
‘S2343
‘S2313
‘S4414
‘S8515
Classic Classic Classic Classic Classic Classic
‘mega103
Mega
PINS
20
8
8
20
40/44
40/44
64
FLASH
1K
2K
2K
2K
4K
8K
128K
0+32
128+32
128+32
128+32
256+32
512+32
4K+32
64
128
128
128
256
512
4K
UART
-
-
-
YES
YES
YES
YES
PWMs
-
-
-
1
2
2
4
ADC(10-bits)
-
-
-
-
-
-
8Ch
AVAILABLE
NOW
NOW
NOW
NOW
NOW
NOW
NOW
SRAM+REGs
EEPROM
Flash MCU
AVR Product Line cont.
‘S4434
FAMILY
PINS
FLASH
‘S8535
‘S4433
‘S2333
‘mega161
‘mega163
‘mega603
Classic Classic
Classic
Classic
Mega
Mega
Mega
40/44
40/44
28/32
28/32
40/44
EgaAVR
40/44
64
4K
8K
4K
2K
16K
16K
64K
512+32
256+32
128+32
1K+32
1K+32
4K
SRAM+REGs 256+32
EEPROM
256
512
256
128
512
512
2K
UART
YES
YES
YES
YES
YES
YES
YES
PWMs
3
3
1
1
4
4
4
ADC(10-bits)
8Ch
8Ch
6Ch
6Ch
-
8Ch
8Ch
AVAILABLE
NOW
NOW
NOW
NOW
3Q00
3Q00
NOW
Flash MCU
AVR Product Line cont.
‘tiny10/11 ‘tiny12
FAMILY
‘tiny15
‘tiny19
‘tiny22
‘tiny28
‘tiny26
Tiny
Tiny
Tiny
Tiny
Tiny
Tiny
Tiny
8
8
8
28
8
28
20
FLASH
1K
1K
1K
1K
2K
2K
2K
SRAM+REGs
32
32
32
32
128+32
32
64+32
-
64
64
-
128
-
128
NO
YES
YES
NO
YES
NO
YES
I/O’s
6
6
6
20
5
20
16
T/C
1
1
2
1
1
1
2
PWM
-
-
1
-
-
-
2
ADC(10-bits)
-
-
4Ch
-
-
-
11Ch
AVAILABLE
NOW
2Q00
2Q00
2Q00
NOW
2Q00
PINS
EEPROM
ISP
2Q00
Flash MCU
AT90S1200
·
·
·
·
·
·
·
·
·
World’s Highest Performance 8-bit MCU
20-pin Device
1 Kbytes ISP Flash
64 bytes ISP EEPROM
15 Programmable I/O lines
8-bit Timer Counter
1 External Interrupt
Analog Comparator
RC-Oscillator
Flash MCU
AT90S4414 / AT90S8515
·
·
·
·
·
·
·
·
·
·
·
40-pin Device
4/8 Kbytes of ISP Flash
256/512 bytes of ISP EEPROM
256/512 bytes SRAM
Full Duplex UART
SPI-Serial Interface
8- and 16-bits Timer/Counter
Dual PWM
2 External Interrupts
Analog Comparator
Fast start up possibility
Flash MCU
AT90S2313 / AT90LS2313
·
·
·
·
·
·
·
·
·
·
·
20-pin Device
2 Kb ISP Flash
128 bytes ISP EEPROM
128 bytes SRAM
8-bit Timer Counter
16-bit Timer Counter with capture/compare
Full Duplex UART
Selectable 8, 9 or 10-bit PWM
2 External interrupts
On Chip Analog Comparator
Fast start up possibility
Flash MCU
AT90S2323 / AT90LS2323
·
·
·
·
·
·
·
·
8-pin Device
2 Kbytes ISP Flash
128 bytes ISP EEPROM
128 bytes SRAM
8-bit Timer/Counter0
1 External Interrupt
3 I/O Pins
External Crystal Oscillator Only
Flash MCU
AT90S2343 / AT90LS2343
·
·
·
·
·
·
8-pin Package
2 Kbytes ISP Flash
128 bytes ISP EEPROM
128 bytes SRAM
8 bit timer
5(4) I/O Pins
 Int. RC: 5 I/O pins + RESET, VCC and GND
 Ext. Clock: 4 I/O pins + RESET, XTAL1, VCC and GND
· External Clock or Internal RC Oscillator
 Selected with fuse
· Fast Wake-up
Flash MCU
AT90S4433/ AT90S2333
·
·
·
·
·
·
·
·
28 Pins package
4/2 Kb ISP Flash
128 bytes ISP EEPROM
256/128 bytes SRAM
8-bit Timer Counter
16-bit Timer Counter with capture/compare/PWM
Full Duplex UART
10-bit ADC with 6 Multiplexed Inputs
Flash MCU
AT90S4434 / AT90LS4434
• 40/44-pin Device
• 10-bit ADC with 8 Multiplexed Inputs
• 3.6 - 14.3 ksamples/sec (Single Conversion Mode)
• 3.9 - 15.4 ksamples/sec (Free Running Mode)
• RTC with Separate 32 kHz Oscillator
• Power Save Mode: Only RTC running <7mA power consumption
• Functionally Equal to AT90S4414
• New Pin-out to improve ADC noise immunity
• No External SRAM interface
• Port C pin order swapped
Flash MCU
AT90S8535 / AT90LS8535
• 40/44-pin Device
• 10-bit ADC with 8 Multiplexed Inputs
• 3.6 - 14.3 ksamples/sec (Single Conversion Mode)
• 3.9 - 15.4 ksamples/sec (Free Running Mode)
• RTC with Separate 32 kHz Oscillator
• New Power Save Mode: Only RTC Running
• Functionally Equal to AT90S8515
• New Pin-out to improve ADC noise immunity
• No External SRAM interface
• Port C pin order swapped
Flash MCU
ATmega103 / ATmega103L
•
•
•
•
•
64-pin Device (48 I/O, 16 Special Function)
128 Kbytes ISP Flash
4Kbytes SRAM
4Kbytes EEPROM
10-bit ADC with 8 Multiplexed Inputs
• 3.3 - 13.3 ksamples/sec (Single Conversion Mode)
• 3.6 - 14.3 ksamples/sec (Free Running Mode)
• Separate 32 kHz Oscillator with RTC
• Power Save Mode: Only RTC running <7mA power consumption
Flash MCU
ATmega603 / ATmega603L
•
•
•
•
•
64-pin Device (48 I/O, 16 Special Function)
64 Kbytes ISP Flash
4Kbytes SRAM
2Kbytes EEPROM
10-bit ADC with 8 Multiplexed Inputs
• 3.3 - 13.3 ksamples/sec (Single Conversion Mode)
• 3.6 - 14.3 ksamples/sec (Free Running Mode)
• Separate 32 kHz Oscillator with RTC
• Power Save Mode: Only RTC running <7mA power consumption
Flash MCU
ATmega161 / ATmega161L
• 40/44-pin Device
• 16 Kbytes ISP Flash with Optional Boot Sector for Selfprogramming of program and data memories.
• 1Kbytes SRAM
• 512bytes EEPROM
• Separate 32 kHz Oscillator with RTC
• Power Save Mode: Only RTC running <7mA power consumption
• On-Chip 2cycle Multiplier
• 4 ch PWM, Dual UART and SPI
• Programmable Brown-Out detection circuit
Flash MCU
ATmega163 / ATmega163L
• 40/44-pin Device
• 16 Kbytes ISP Flash with Optional Boot Sector for Selfprogramming of program and data memories.
• 1Kbytes SRAM & 512bytes EEPROM
• 10-bit ADC with 8 Multiplexed Inputs
• 3.3 - 13.3 ksamples/sec (Single Conversion Mode)
• 3.6 - 14.3 ksamples/sec (Free Running Mode)
• Separate 32 kHz Oscillator with RTC
• Power Save Mode: Only RTC running <7mA power consumption
• On-Chip 2cycle Multiplier
• 4 ch PWM, Dual UART and SPI
• Programmable Brown-Out detection circuit
Flash MCU
Tiny 10/11
·
·
·
·
·
·
·
·
8 Pins package
1 Kb ISP Flash
6 Programmable I/O lines
1 external interrupt
8-bit Timer Counter
Analog Comparator
Wake up on pin change
Ultra low cost OTP version(Tiny10)
Flash MCU
Tiny 12/12L/12V
·
·
·
·
·
·
·
·
·
8 Pins package
1 Kb ISP Flash
64B On-chip EEPROM
6 Programmable I/O lines
1 external interrupt
8-bit Timer Counter
Analog Comparator
Wake up on pin change
Internal Calibrated RC oscillator
Flash MCU
Tiny 15/15L
·
·
·
·
8 Pins package & 6 Programmable I/O lines
1 Kb ISP Flash & 64B On-chip EEPROM
Two 8-bit Timer Counter & 150KHz High speed PWM
4Ch 10bit ADC (One differencial Input with Optional Gain of
20x) & Analog Comparator
· Internal 1.6MHz Tuneable oscillator
· Programmable Brown-Out detection circuit
Flash MCU
Tiny 22/22L
·
·
·
·
·
·
·
·
8 Pins package
2 Kb ISP Flash
128B SRAM & EEPROM
5 Programmable I/O lines
1 external interrupt
8-bit Timer Counter
Wake up on pin change
Selectable On-chip RC oscillator
Flash MCU
Tiny 26/26L
·
·
·
·
·
·
·
·
20 Pins package
2 Kb ISP Flash, 64B SRAM & 128B EEPROM
16 Programmable I/O lines
8-bit Timer Counter & 2Ch High speed PWM
External interrupt & Pin change interrupt on 8 pins
Internal Calibrated RC oscillator
Programmable Brown-Out detector
10-bits ADC
- 11 single ended, 6 differential ADC channels
- 2 differential ADC Channels with Optional Gain of 20x
Flash MCU
AVR Road Map
What will we see in the near future?
Flash MCU
The Three AVR Families
• megaAVR ATmegaXXX ( 16kB - 128 kB)
• Targets complex applications with requirements for large program memories
• classicAVR AT90XXXX
( 1- 8kB )
• Targets medium-range applications where high throughput and low power is
important
• tinyAVR
ATtinyXX
( 1 - 2kB )
• Targets cost-sensitive applications in the very low end of the 8-bit MCU
market
Flash MCU
FLASH DENSITY
AVR PRODUCT ROADMAP: 1998
megaAVR FAMILY
16KB TO 128KB
classicAVR FAMILY
1KB TO 8KB
tinyAVR FAMILY
1KB & 2KB
DEVICE COMPLEXITY
Flash MCU
tinyAVR applications
•
•
•
•
•
•
•
•
•
Automotive low-end control applications
Toys
Games and Game-Cards
PC Motherboard Connector Control
Security Controller for mobile Phones (SIS Code)
Battery Chargers
Communication IF controllers
White and Brown Goods
Smoke Detectors
Flash MCU
classicAVR applications
•
•
•
•
•
•
•
•
PC Modems
Cable Modems
Battery Chargers (advanced)
Smart Cards and Smart Card Readers
Tool Road Pay Tags
Set-top Boxes
Pay-TV Decoders
Various Industrial Control Applications
Flash MCU
megaAVR applications
•
•
•
•
•
•
Analog Mobile Phones (NMT, ETACS, AMPS, and D-AMPS)
Digital Mobile Phones (GSM and CDMA)
Printers and Printer Switches/Controllers
Fax Controller
Disk Drive Controllers
CD-ROM Controllers
Flash MCU
In-System Programmable Flash and
EEPROM
Now Offered on an MCU by a
technology leader in Non-Volatile
memories
Flash MCU
This is ISP Flash and EEPROM
5-wire
serial programming
interface
Your device sits in the application. It is clocked from
the application clock, and VCC can be as low as 2.7V.
Now, with four logical signals + Ground, you can
REPROGRAM THE FLASH AND THE EEPROM
NO +12V PROGRAMMING VOLTAGE REQUIRED!
Flash MCU
Just Imagine...
• No OTP parts thrown away
• No 5-minute UV erase time
• No sleepless nights after mask tape-out
• No stocking of multiple system versions
• No surprises in moving from OTP to mask
• No 10-week lead time
… instead ...
• Easy update of new features
• Easy bug fix
• Easy testing
• Easy in-line calibration
Flash MCU
AVR for ASIC
•
•
•
•
•
RTL softcore enables a varity of processes
RTL for Standard I/O modules
AVR ASIC ICE available with reference designs
AVR ASIC handbook
Ready to go NOW !
Flash MCU
The AVR Offers...
…Industry’s Highest 8-bit Performance
…Low Power Consumption
…a broad Family of MCUs
…a Variety of Peripherals
…excellent C Language Code Density
…In-System Programmable Flash and EEPROM
Flash MCU
Instruction Set & Architecture
A Guided Tour Through the
Architecture, Instruction by Instruction
Flash MCU
Instruction Set General Features
• All Instructions (with a few exceptions) are
16 Bits Wide
• Most Instructions are Executed in One
Clock Cycle
Flash MCU
Instruction Classes
•
•
•
•
Arithmetic/Logic Instructions
Data Transfer Instructions
Program Control Instructions
Bit Set/Test Instructions
Flash MCU
Arithmetic/Logical Instruction
•
•
•
•
•
Add / Increment
Subtract / Decrement
Compare
Logical (AND, OR, XOR)
Shift / Rotate
All True Single Cycle
Flash MCU
Add Instructions
•
•
•
•
“ADD” Add Two Registers
“ADC” Add Two Registers and Carry
“INC” Increment a Register
“ADIW”Add Immediate to Word *
* Works on the 4 Uppermost Register Pairs
Flash MCU
Subtract Instructions
•
•
•
•
“SUB” Subtract Two Registers
“SBC” Subtract with Carry Two Registers
“SUBI” Subtract Immediate from Register*
“SBCI” Subtract with Carry Immediate
from Register*
• “DEC” Decrement Register
• “SBIW “ Subtract Immediate From Word**
*
**
Works on Registers R16 - R31
Works on the 4 Uppermost Register Pairs
Flash MCU
Executing “subi r16,k”
Instruction Word
Register File
Immediate Operand
Instruction
ALU
Flash MCU
Compare Instructions
• “CP”
Compare Two Registers
• ”CPC” Compare with Carry Two
Registers
• “CPI” Compare Register and Immediate*
• “CPSE” Compare Two Registers and Skip
Next Instruction if Equal
*
Works on Registers R16 - R31
Flash MCU
16/32-Bit Data Support
The AVR Supports Code and Time Efficient 16
and 32-bit Arithmetic's Through the Following:
• Single Cycle Execution
• A Register File That Holds Several 16/32-Bit Values
• Carry and Zero Flag Propagation on Subtract and
Compare
Flash MCU
Subtract Two 16-Bit Values
Without Zero Flag Propagation
R1:R0 - R3:R2 ($E104 - $E101)
R1
R0
Z
E1
04
X
sub r0,r2
E1
03
0
sbc r1,r3
00
03
1
Wrong!
Flash MCU
Subtract Two 16-Bit Values
With Zero Flag Propagation
R1:R0 - R3:R2 ($E104 - $E101)
R1
R0
Z
E1
04
X
sub r0,r2
E1
03
0
sbc r1,r3
00
03
0
Correct!
Flash MCU
Compare Two 32-Bit Values
Example: Compare R3:R2:R1:R0 and R7:R6:R5:R4
cp
cpc
cpc
cpc
r0,r4
r1,r5
r2,r6
r3,r7
At the end, the Status Register Indicates Equal,
Higher, Lower, Greater (signed), Less Than (signed).
Besides, it takes only 4 instructions and 4 clock
cycles to do it...
Flash MCU
Logical Instructions
• “AND” Logical AND Two Registers
• “ANDI” Logical AND Immediate and
Register *
• “OR”
Logical OR Two Registers
• “ORI”
Logical OR Immediate and
Register *
• “EOR” Logical XOR Two Registers
*
Works on Registers R16 - R31
Flash MCU
Shift / Rotate Instructions
•
•
•
•
•
“LSL”
“LSR”
“ROL”
“ROR”
“ASR”
Logical Shift Left
Logical Shift Right
Rotate Left Through Carry
Rotate Right Through Carry
Arithmetic Shift Right
Flash MCU
Shift / Rotate Operations
MSB
LSR
ROR
ASR
0
Register
LSB
Carry
Flash MCU
Data Transfer Instruction Types
# of Cycles
• Data SRAM Register File
• Program Memory  Register File
• I/O Memory Register File
(2)
(1/2)
(1)
Flash MCU
The 5 Memory Areas
•
•
•
•
•
General Purpose Register File
Flash Program Memory
SRAM Data Memory
I/O Memory
EEPROM Data Memory
32 Bytes
8 MB
8 MB
64 Bytes
8 MB
Flash MCU
Memory Interconnections
Program Memory
Register File
I/O Memory
SRAM
EEPROM
Flash MCU
AVR Pointer Structure
R0
R1
R2
R3
R26
R27
R28
R29
R30
R31
XL
XH
YL
YH
ZL
ZH
Register File
X Pointer
Y Pointer
Z Pointer
Flash MCU
Data SRAM  Register File
Instructions
• “LD Rd,<PTR>”
Load Indirect
• “LD Rd,<PTR>+”
Load Indirect with
Post-Increment
• “LD Rd,-<PTR>”
Load Indirect with
Pre-Decrement
• “LDD Rd,<PTR>+q”
Load Indirect with
Displacement (0-63)*
• “LDS Rd,<ADDR>“
Load Direct from
SRAM (16-bit ADDR)**
*
**
PTR =X, Y or Z
Parts with SRAM > 64k bytes, memory page selected
using the RAMPZ register
Flash MCU
Data SRAM  Register File
Instructions
• “ST <PTR>,Rd”
• “ST <PTR>+,Rd”
Store Indirect
Store Indirect with
Post-Increment
• “ST -<PTR>,Rd”
Store Indirect with
Pre-Decrement
• “STD <PTR>+q,Rd”
Store Indirect with
Displacement (0-63) *
• “STS <ADDR>,Rd”
Store Direct from
SRAM (16-bit ADDR)**
*
**
PTR = X, Y or Z
Parts with SRAM > 64k bytes, memory page selected
using the RAMPZ register
Flash MCU
Move 16 Bytes SRAM  RF...
Example:
loop:
.def
.def
temp=r16
cnt=r17
;temporary storage register
;loop counter
ldi
ldi
clr
clr
ldi
ld
st
dec
brne
ZH,high(SRAM_LOCATION) ;init Z pointer
ZL,low(SRAM_LOCATION)
YH
;init Y pointer
YL
cnt,16
;init loop counter
temp,Z+
;get data from SRAM
Y+,temp
;store data in RF
cnt
;decrement counter
loop
;loop more if not done
Flash MCU
… and Store Back
Example (Continued):
loop:
ldi
ld
st
dec
brne
cnt,16
temp,-Y
Z-,temp
cnt
loop
;init loop counter
;get data from RF
;store data in SRAM
;decrement counter
;loop more if not done
Flash MCU
Data Transfer RF 
SRAM Stack Instructions
• “PUSH”
PUSH a register on the stack
• “POP”
POP a register from the stack
Flash MCU
Data Transfer Prog. Memory
 RF Instructions
• “LDI”
Load a Register with an
Immediate Value (1 Cycle) *
• “LPM” Transfer a byte from Program
Memory@Z to R0 (2 Cycles) **
* Works on R16 - R31,
** Available on parts with SRAM, only
Flash MCU
The LPM Instruction
MSB
Z Pointer
Selects Program Memory Address
The byte pointed to by Z is transferred to R0
LSB
Selects
Low/High Byte
Flash MCU
Register File I/O Memory
Transfer Instructions
• OUT
• IN
Transfer a Byte from RF to I/O
Transfer a Byte from I/O to RF
Flash MCU
Program Control Instruction Types
• Unconditional Jumps
• Conditional Branches
• Subroutine Call and Returns
Flash MCU
Unconditional Jump Instructions
• “RJMP” Relative Jump *
• “JMP” Absolute Jump **
• “IJMP” Indirect Jump to Program
Location@Z
- Reaches ± 2K instructions from current program location.
- Wrap-around
** 4-Byte Instruction
*
Flash MCU
Instruction Fetch/Execution
Instructions are Sequential
Fetch
Execute
T1
T2
T3
INSTR n+1
INSTR n+2
INSTR n+3
INSTR n
INSTR n+1
INSTR n+2
Flash MCU
Instruction Fetch/Execution
One Instruction is a Jump
Fetch
Execute
T1
T2
INSTR n+1
INSTR m
INSTR m+1
INSTR n
INSTR n
INSTR m
(Jump to m)
Reject
T3
Flash MCU
Conditional Branch Instructions
(Flag Set)
•
•
•
•
•
•
•
•
•
“BREQ”
“BRSH”
“BRGE”
“BRHS”
“BRCS”
“BRMI”
“BRVS”
“BRTS”
“BRIE”
Branch if Equal
Branch if Same or Higher
Branch if Greater or Equal (Signed)
Branch if Half Carry Set
Branch if Carry Set
Branch if Minus
Branch if Overflow Flag Set
Branch if T Flag Set
Branch if Interrupt Enabled
Flash MCU
Conditional Branch Instructions
(Flag Clear)
•
•
•
•
•
•
•
•
•
“BRNE”
“BRLO”
“BRLT”
“BRHC”
“BRCC”
“BRPL”
“BRVC”
“BRTC”
“BRID”
Branch if Not Equal
Branch if Lower
Branch if Less Than (Signed)
Branch if Half Carry Clear
Branch if Carry Clear
Branch if Plus
Branch if Overflow Flag Clear
Branch if T Flag Clear
Branch if Interrupt Disabled
Flash MCU
The Status Register - SREG
7
Interrupt Enable
I
Enables Global Interrupts when Set
T Flag
T
Source and Destination for BLD and BST
Half Carry
H
Set if an Add/Sub. has Carry between Bits 4&3
Signed Flag
S
Used for Signed Tests
Overflow Flag
V
Set if an Add/Sub Results in Signed Overflow
Neagative Flag
N
Set if a Result is Negative
Zero Flag
Z
Set if a Result is Zero
Carry Flag
C
Set if an Add/Subtract has Carry
0
Flash MCU
Branch on SREG Settings
7
Branches
if Bit Clear
BRID
I
BRIE
BRTC
T
BRTS
BRHC
H
BRHS
BRGE
S
BRLT
BRVC
V
BRVS
BRPL
N
BRMI
BRNE
Z
BREQ
BRSH, BRCC
C
BRCS, BRLO
0
Branches
if Bit Set
Flash MCU
Subroutine Call and Return
Instructions
• “RCALL”
• “CALL”
• “ICALL”
• “RET”
• “RETI”
Relative Subroutine Call *
Absolute Subroutine Call **
Indirect Subroutine Call to
Routine @Z
Return from Subroutine
Return from Interrupt
Routine
- Reaches ± 2K instructions from current program location
- Wrap-around
** 4-Byte Instruction
*
Flash MCU
Bit Set and Bit Test Instructions
• “SBR”
• “SBI”
Set Bit(s) in Register *
Set Bit in I/O Register **
• “SBRS” Skip if Bit in Register Set
• “SBIS” Skip if Bit in I/O Register Set **
* Works on Registers R16 - R31
** Works on I/O Addresses $00 - $1F
Flash MCU
Bit Clear and Bit Test Instructions
• “CBR”
• “CBI”
Clear Bit(s) in Register *
Clear Bit in I/O Register **
• “SBRC” Skip if Bit in Register Clear
• “SBIC” Skip if Bit in I/O Register Clear **
* Works on Registers R16 - R31
** Works on I/O Addresses $00 - $1F
Flash MCU
Interrupt System
and
Sleep Modes
Flash MCU
Interrupt System Features
• Short Response Time (4 Clock Cycles + RJMP to
Routine)
• Automatic Interrupt Flag Clearing
• Automatic Disable of Other Interrupts Inside the
Interrupt Routine
Flash MCU
Interrupt Vector Example
$0000rjmp RESET;Reset Vector
$0001rjmp IRQ0
;IRQ0 Vector
$0002rjmp IRQ1
;IRQ1 Vector
IRQ0:
$0003<opcode>
$0004<opcode>
…
$xxxx<opcode>
$xxxxreti
;IRQ0 Routine
;Ret. from Interrupt
Flash MCU
Executing an Interrupt
Episode 1, Interrupt in the Main Program
$0123mov
$0124add
$0125adc
$0126lsl
$0127clc
Interrupt
•
•
•
•
•
r16,r0
r20,r0
r21,r1
r0
“lsl r0” is Completed
$0127 is Pushed onto the Stack
The Interrupt Flag is Cleared
The I-bit in SREG is Cleared
The Program Jumps to the IRQ Vector
4 Clock Cycles
Flash MCU
Executing an Interrupt
Return
Episode 2, The Interrupt Vector and Routine
$0000RJMP RESET
;Reset Vector
$0001RJMP IRQ0
;IRQ0 Vector
$0002RJMP IRQ1
;IRQ1 Vector
IRQ0:
;IRQ0 Routine
$0003in
r0,PINB
$0004out PORTD,r0
$0005reti
;Ret from IRQ0
•
•
•
The I-bit in SREG is Set
$0127 is Popped of the Stack
Program Execution Resumes from $0127
4 Clock Cycles
Flash MCU
Sleep Modes
• Idle Mode
• Power Down Mode
Sleep Mode is entered by executing the “SLEEP”
Instruction with the “SE” Bit in the “MCUCR”
Register Set.
If the “SM” Bit in “MCUCR” is set, the
MCU enters Power Down Mode when “SLEEP”
is executed
Flash MCU
Idle Mode
•
•
•
•
CPU is Stopped
XTAL Oscillator Runs
Timer/Counters and other Peripherals Operate
Reset + All Enabled Interrupts Can Wake Up the MCU
Flash MCU
Power Down Mode
•
•
•
•
CPU is Stopped
XTAL Oscillator is Stopped
Timer/Counters and Other Peripherals are Stopped
Internal RC Oscillator Runs if the Watchdog is
Enabled.
• Reset + External Level Interrupt Can Wake up the
MCU
Flash MCU
Power Save Mode
• CPU is Stopped
• XTAL Oscillator is Stopped
• Timer 2 is clocked asynchronously
– Optimized for external 32.768 Khz crystal
• Power consumption < 7uA@5V
• Easy Real Time Clock implementation
Flash MCU
Wake-Up from Sleep Mode
• RESET:
The MCU Starts Execution
from the Reset Vector
• INTERRUPT:
The MCU Enters the
Interrupt Routine, Runs it
and Resumes Execution
from the Instruction
following “SLEEP”.
Flash MCU
Peripherals
I/O Ports
Timer/Counters
Comparator
Watchdog
UART
A/D converter
Flash MCU
I/O Ports General Features
•
•
•
•
•
•
•
Push-Pull Drivers
High Current Drive (sinks up to 40 mA)
Pinwise Controlled Pull-Up Resistors
Pinwise Controlled Data Direction
Fully Synchronized Inputs
Three Control/Status Bits per Bit/Pin
Real Read-Modify-Write
Flash MCU
3 Control/Status Bits
per Pin
• DDx
Data Direction Control Bit
• PORTx Output Data or Pull-Up Control
Bit
• PINx
Pin Level Bit
X = A, B, C, ...
Flash MCU
Default Configuration
DDx
0
Pull-Up
PORTx
0
PINx
Physical Pin
?
?
Direction:
Pull-Up:
INPUT
OFF
Flash MCU
Switch On Pull-Up
DDx
0
Pull-Up
PORTx
1
PINx
Physical Pin
?
?
Direction:
Pull-Up:
INPUT
ON
Flash MCU
Port is Output
DDx
1
Pull-Up
PORTx
1
PINx
Physical Pin
1
1
Direction:
Pull-Up:
OUTPUT
OFF
Flash MCU
Why Three Addresses?
Why not let WRITE PORTx write the LATCH
and
READ PORTx read the PINS?
(just like Microchip, Hitachi, Motorola...)
A Two-address Port means NO
REAL Read-Modify-Write
Flash MCU
The Two-Address Problem
Example:
• I/O Type:
• Configuration:
• Software Task:
PORTx Reads the Pin
and Writes the Latch
Some PORTx Pins are
Outputs, Others are Inputs,
Inputs Have Pull-Ups on
Set One of the Output Pins
PROBLEM!
Flash MCU
The Two-Address Problem
(Continued)
• Setting an I/O Pin is Done Like This:
– Read PORTx
(Read)
– OR With All Zeros Except Bit to be Set
(Modify)
– Write PORTx
(Write)
• If the Signal on an Input Pin is Low When PORTx is
Read...
Write Back WILL TURN OFF THE PULL-UP.
Flash MCU
From the PIC16C64 Datasheet:
“Reading the PORT register, reads the values of the PORT pins.
Writing to the PORT register writes the value to the PORTB latch.
When using read modify write instructions (ex. BCF, BSF, etc.) on
a PORT, the value of the PORT pins is read, the desired operation is
done to this value, and the value is then written to the PORT latch”
.”
…
“…care must be exercised if a write followed by a read operation is
carried out on the same I/O port. The sequence of instructions should
be such to allow the pin voltage to stabilize (load dependent) before the
next instruction … otherwise, the previous state of that pin may be read
into the CPU rather than the new state … it is better to separate these
instructions with a NOP or another instruction not accessing this I/O port.”
Flash MCU
From HITACHI’s H8/300
Programming Manual:
“BSET, BCLR, … are read-modify-write instructions. They read a
byte of data, modify one bit in the byte, then write the byte back.
Care is required when these instructions are applied to registers
with write-only bits and to the I/O port registers.”
…
“Programming Solution: The switching of the pull-ups can be
avoided by storing the same data both in the port data register
and in a work area in RAM”
Flash MCU
Timer/Counters
Standard AVR Timer/Counter Modules
• Timer/Counter0 - 8 Bit
• Timer/Counter1 - 16 Bit
• Timer/Counter2 - 8 Bit
Flash MCU
General T/C Features
• Clock Prescaling Options: 1, 8, 64, 256, 1024
• Can Run at Undivided XTAL Frequency (High
Resolution)
• Can be Set to Any Value at Any Time
• Can be Clocked Externally by Signals with Transition
Periods down to XTAL/2
• Can be Clocked Externally on both Rising and Falling
Edge.
Flash MCU
Timer/Counter0
• 8-Bit
• Overflow Interrupt
Flash MCU
T/C0 Block Diagram
Data Bus
Timer Interrupt Mask
Register (TIMSK)
Timer Interrupt Flag
Register (TIFR)
Control Logic
8-Bit Timer/Counter
T/C0 Control Register
(TCCR0)
Flash MCU
Timer/Counter1
•
•
•
•
•
16-Bit
Overflow Interrupt
Output Compare Function with Interrupt
Input Capture with Interrupt and Noise Canceler
10, 9 or 8-Bit PWM Function
Flash MCU
T/C1 Block Diagram
Data Bus
Timer Interrupt Mask
Register (TIMSK)
Timer Interrupt Flag
Register (TIFR)
Control Logic
T/C0 Control Register A
(TCCR1A)
T/C0 Control Register B
(TCCR1B)
16-Bit Timer/Counter
Input Capture1 Register
(ICR1)
Timer/Counter1 Output
Compare Reg. (OCR1)
16-Bit Comparator
Flash MCU
Timer/Counter2
•
•
•
•
•
8-Bit
Overflow Interrupt
Output Compare Function with Interrupt
8-Bit PWM Function
Real Time Clock function
Flash MCU
T/C2 Block Diagram
Data Bus
Timer Interrupt Mask
Register (TIMSK)
Timer Interrupt Flag
Register (TIFR)
Control Logic
T/C2 Control Register
(TCCR2)
8-Bit Timer/Counter
8-Bit Comparator
Timer/Counter2 Output
Compare Reg. (OCR2)
Asynch. Status
Register(ASSR)
Flash MCU
Output Compare Features
• Compare match can control an external pin
(Rise, Fall or Toggle) even if the Interrupt is
disabled.
• As an option, the timer can be automatically
cleared when a compare match occurs.
Flash MCU
Input Capture Features
• Capture Can Trigger on Rising or Falling Edge
(Optional)
• The Input Capture Noise Canceler will not
trigger the Capture until 4 Subsequent samples
of the same value are seen.
The Noise Canceler is Optional
Flash MCU
PWM Features
•
•
•
•
•
Selectable 10, 9 or 8-Bit Resolution.
Frequency @ 10 MHz (8-bit): 19 KHz
Centered Pulses
Glitch-Free Pulse Width Change
Selectable Polarity
Flash MCU
PWM Operation
Compare
Value 2
Compare
Value 1
PWM
Output 1
PWM
Output 2
Timer
Value
Flash MCU
Analog Comparator Features
• Comparator has its own Interrupt on Output
Transitions
• Interrupt has selectable trigger on Rise, Fall or Toggle
• The Comparator Output can be Connected to the Input
Capture of Timer/Counter1
– Enables Pulse-Width Measurement of Analog Signals
– Enables Easy Implementation of Dual Slope ADC
Flash MCU
A/D Converter
•
•
•
•
•
•
Succesive Approximation A/D
10 Bit resolution
1/2 LSB Accuracy
65-260 uS conversion time
8 Multiplexed input channels
Interrupt on AD conversion complete
Flash MCU
A/D converter
Data Bus
ADC Control and Status
Register(ADCSR)
ADC dataregister
(ADCH/ADCL)
Succesive approximation logic
10-bit DAC
ADC multiplexer
select(ADMUX)
8Channel
Mux
Analog
input
Flash MCU
Watchdog
• Clocked from Internal 1 MHz R-C Oscillator
• Time-Out Adjustable 16 - 2048 ms.
• Watchdog Timer Reset is done by executing the
“WDR” instruction
Flash MCU
UART Features
•
•
•
•
•
•
Full Duplex
8 or 9 Data Bits
Framing Error Detection
False Start Bit Detection
Noise Canceling
High BAUD Rates at low XTAL Frequencies
E.g. 115,200 Baud at 1.8432 MHz
• Can run at Practically any Baud Rate
• Three Interrupts with Separate Vectors
Flash MCU
Development Tools
Flash MCU
Development Tools Overview
•
•
•
•
•
•
•
•
ANSI compliant C Compiler
Macro-Assemblers
Linker/Librarian
Debugger/Simulator
RTOS
In-Circuit Emulator
Evaluation boards
Programmers
Flash MCU
In-Circuit Emulator
 Easy to use MS-Windows interface
 Unlimited number of Breakpoints
 Trace buffer
 Logic analyzer interface
 External trigger inputs/outputs
 Reconfigurable I/O
Flash MCU
Event Memory
• Breakpoints
– Eight different Breakpoints for each location
– Break mask register
• Control
– Two bits for trace control
– Three bits for external triggers
– Three bits for auxillary use
Flash MCU
Trace buffer
• Control in Event memory
– Trace on, Trace off, Toggle, No action
• 32K deep
• 96 bit wide
Flash MCU
Connectors
• Two connectors for logic analyzer
– Program memory address (20 bit)
– Program memory data (16 bit)
– Clock
• Auxillary connector
– Trigger inputs
– Trigger outputs
Flash MCU
Flash MCU
AVR Studio
•
•
•
•
•
Easy to Use MS-Windows interface
Controls the AVR In-Circuit Emulator
Uses AVR Simulator if AVR ICE not present
C and Assembly source level debugging
Reads different object formats, including UBROF
from IAR development tools
• Project information
Flash MCU
AVR Studio Source View
• C and Assembly display
• Toggle execution level
• Breakpoints insertion and
removal
• Run to cursor
• Module selection
• Source code search
Flash MCU
AVR Studio Symbol Watch
•
•
•
•
Maintains scope information
Binds watches automatically
Simple variables
Arrays, Structs, Unions and Pointers
Flash MCU
AVR Studio Register View
• Simple window to
view register
contents
• Registers can be
modified when
execution is stopped
• Red colour on active
registers
Flash MCU
AVR Studio Memory View
• SRAM, Program Memory, EEPROM and I/O
• Various representations
• Modifications possible when execution stopped
Flash MCU
AVR Studio Processor View
• Displays essential
information about
debug target
• Values modifiable
when execution
stopped
Flash MCU
AVR Studio I/O Views
• Specialized views for I/O
devices
–
–
–
–
–
–
–
Timer
UART
Port
SPI
Analog Comparator
EEPROM
ADC
Flash MCU
IAR Development Tools for
 Fully ANSI compliant C Compiler
 Built-In AT90S specific optimizer
 Includes Embedded Workbench
 Assembler, Librarian and Linker
 C And Assembly level debugger
 Windows-95, Win 3.11, Windows NT and DOS
Flash MCU
Chip Specific Extensions
•
•
•
•
•
•
Initialization function for Hardware setup
Special Function Register (SFR) for I/O access
Interrupt functions
Monitor functions for critical regions
Routines for accessing Flash
Intrinsic functions:
– SEI, CLI, NOP, OPC, LPM, SLEEP, WDR
• EEPROM access routines
– EEPUT, EEGET
Flash MCU
Example: SFR / Intrinsics
sfrb
sfrb
MCUCR = 0x35;
GIMSK = 0x3B;
int __low_level_init(void)
{
GIMSK = 0xC0; /* Enable ext interrupts */
MCUCR = 0x0F; /* Extern int on ris edge */ _SEI();
/* Enable interrupts */
return(1);
}
Flash MCU
Example: Interrupts
interrupt[TIM1_CAPT_vect] void tim1capt(void)
{
int uCapture;
uCapture = ICR1 ;
if(uCapture > CONST)
{
…
}
}
Flash MCU
Example: Monitor functions
monitor int P(char *flag)
{
if(!*flag)
return(*flag = 1);
else
return(0);
}
Flash MCU
AVR Development Tools
• Complete development tools package
• State-of-the-art graphical user interface
• Effective C Compiler and processor core
results in compact code
• Compiler well suited for embedded
applications
Flash MCU
Hands On Training
Using the AVR Assembler
Flash MCU
Assembly
• Full control of Resource
Usage
• Compact and fast code in
small applications
• Inneffecient code in larger
applications
• Cryptical code
• Hard to maintain
• Non-portable
vs.
C
• Limited control of Resource
usage
• Larger/slower code in small
applications
• Efficient code in larger
applications
• Structured code
• Easy to maintain
• Portable
Flash MCU
Assembler exercise 1
• Write a assembler program that reads input on the
serial port and send it as hex value to the LEDS
• Store the data in SRAM until LF(Line Feed) is pressed
(0x0A)
• Convert the data to capital letters and send them on the
serial port
• EXTRA: Write “WORKSHOP” on the serial port after
RESET (Tip: use LPM)
Flash MCU
Hints and tricks
• Remember to initalize interrupt vectors and
stack pointer
• Clear high byte of Z pointer
• Data from PC ends with CR(0x0D) and
LF(0x0A)
• Subtract 0x20 to convert to uppercase
Flash MCU
Main Program
Set up interrupt vectors
Init stack pointer
Set PORTB as output
Set baud rate = 9600 @ 4Mhz crystal
Enable UART receive and interrupt
Init Z pointer to RAM address
0x0060
Enable global interrupt
loop: goto loop
Flash MCU
Interrupt Functions
UART_RX:
Store status register
Read UART data register
Output data to port B
If data register not = LF
Store data in RAM
Increment Z pointer
Else
Store LF and CR in RAM
Init Z pointer to RAM address 0x0060
Enable UART Transmit and interrupt
Restore status register
Return
UDRE_empty:
Store status register
Read data from RAM
Increment Z pointer
If Z data not = LF
Convert to capitol letters
Send data to UDR
Else
Send LF to UDR
Init Z pointer to RAM address
0x0060
Enable UART Receive and
interrupt
Restore status register
Return
Flash MCU
Exercise 2
• Convert the program to the IAR assembler
Flash MCU
AVR assembler
.CSEG
.equ label = expression
.equ const = 0x50
.def symbol = register
.def temp = R16
.include “8515def.inc”
Program address is word
.ORG $0005
IAR assembler
NAME routine
#define label expression
-#define const 0x50
#define symbol register
#define temp
R16
#include “io8515.h”
Program address is byte
ORG $0005*2
END
Flash MCU
Optimized for High Level Languages
Flash MCU
High Level Languages
• Increased importance for Microcontrollers
–
–
–
–
–
–
Time to market
Simplified maintenance
Portability
Learning time
Reusability
Libraries
• Potential drawbacks
– Increased codesize
– Decreased speed
Flash MCU
AVR Architecture and Instruction Set influenced
by IAR
• Compiler development project initiated before
Architecture / Instruction Set frozen
• Potential Bottlenecks identified and removed
• IAR feedback reflected in Hardware
• Several iterations
• Result of modifications frequently observed in
generated code
Flash MCU
C-like Addressing Modes
C Source
unsigned char *var1, *var2;
*var1++ = *--var2;
Generated code
LD R16,-X
ST Z+,R16
Flash MCU
Indirect with Displacement
• Effective for accessing arrays and structs
• Autos placed on Software Stack
Flash MCU
Four memory pointers
• Memory to memory
copy
• Minimize pointer
reloading
• High functionality
Flash MCU
16 and 32 bit support
• Carry instructions
–
–
–
–
Addition and Subtraction
Register with register
Register with immediate
Zero flag propagation
SUB R16,R24
SBC R17,R25
SUBI R16,1
SBCI R17,0
All branches can be made based on last result
Flash MCU
16 Bit instructions
• Additions and
Subtractions of
small values
• Ideal for index
variables and
pointer
manipulations
• Software Stack
Flash MCU
Non-destructive comparison
CP
CPC
CPC
CPC
R16,R24
R17,R25
R18,R26
R19,R27
• Compare with carry
instruction
• Zero propagation
• No restoring
necessary
• All conditional
branches available
Flash MCU
Switch Support
• Switches very frequently used by CASE
tools
• Straight forward approach inefficient and
time differentiating
• Indirect jumps well suited for compact
switch constructions
• General library routines manages switches
Flash MCU
Compiler Features
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Fully compatible with the ANSI standard
All required data types supported
Fully reentrant code
General optimizations
AVR specific optimizations
AVR specific extensions
Flash MCU
Optimization
• Code and Speed optimization
• C and Assembly level optimizations
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Algebraic identities
Common subexpression elimination
Removal of branch chains
Condition reversal
Constant folding
Register allocation
Bit operations
Peephole optimizations
Cross jumping and hoisting
Removal of unreachable code
Redundant assignment removal
Flash MCU
Summary
• AVR Architecture originally designed with High
Level Languages in mind
• Cooperation between Atmel and IAR on
Architecture and Instruction Set tuning
• Resulting Compiler generates highly efficient
code
• Incorporated changes frequently exploited in
generated code