Check 2 - PWM
• Announcements
• Overview
• LED Board
• PWM
What’s due:
• Prelab
• Lab
Announcements
• Checkpoint 2 handout has suggestions for the
lab.
• Corrections to older versions of checkpoint 2:
• Add lab9pinout.sch and lab9 LIB file.
• Wire wrap LED board
• To test Mode 1, use :
U:\WVLIB\Transmitter\Transmitter.exe
See Readme file.
Data Path For Checkpoint 2
UART
SRAM
Mode 1 FSM
PWM Block
Switch Bank 5
ROM
LED
Board
Mode 1 FSM
• Very simple
• Wait for a header
• Write 10x14 = 140 bytes to SRAM
• Enable PWM until reset is asserted
• K.I.S.S.
LED Board Protocol
• LED Board Protocol
Col13
Col12
Col11
Col10
Col9
Col8
Col7
Col6
Col5
Col4
Col3
Col2
Col1
Col0
Row0
Row1
Row2
Row3
DATAOUT
CLKOUT
Hex row digit
14 binary Column digits
• Inputs DATAOUT, CLKOUT, DISPE_H
LED Board
• CLKOUT >> 19.2 kHz
CLKOUT
DISPE_H
• 8,9,10 MHz are good
Pulse Width Modulation
LED 1
Time
LED 2
Time
3
PWM Example
Brightness = 4 / 31
ON
OFF
0
1
2
3
4
5
5
6
7
8
9
Debugging Tips
Works in sim, but not in hardware!! What
now?
• Run the TA bit file to verify hardware.
• U:\wvlib\cs150\lab9.bit
• Verify on oscilloscope that clkout is glitchfree.
• Use NUMLED1 to output debugging signals
such as state.
Due next week
• Prelab
• Complete State Transition Diagrams for entire
project.
• PWM and Mode 1 schematics, test scripts and
waveform results.
• Lab
• Display image from Transmitter program
• Partial credit for still image, grey-scale image