VARIABLES
clock ()
MovToObject(obj)
RA Step (direction, steps)
Sits in background and calls
program to execute regularly
Adds the relevant number of steps
to the RA and DEC variables
Sends the correct o/p to the GPIO
to step the stepper motor in
specified direction
Observation()
spiralSearch()
DEC Step (direction, steps)
Runs sequence for set period of
time
Searches for signal using a spiral
pattern
Sends the correct o/p to the GPIO
to step the stepper motor in
specified direction
clockDrive()
Keypad()
Uses an interrupt to increment the
RA VAR by the number of steps
that need to be stepped in RA
Uses an interrupt to read buttons
presses on a direction keypad
Measure()
PMT()
Calls all the subroutines to move
scope between objects and make
the measurements
Returns value of photo multiplier
tube
Save()
PMTcontrol()
Saves the data to disk
Turns on and off the PMT, clears
the values etc.
Once moved to a star location the checkObject sub routine checks the star is there and if
not triggers the spiral search, if this fails the checkObject sub will set a timer that counts
down to zero – this pauses all but the RA clock drive.
CheckObject ()
RTCread()
Once on a star the PMT control start the measurement, and this is read into the aRESULTS
array and then saved to non-volatile memory.
Compares measured with sky to
see if cloudy and if so sets a
variable with a value that
decrements
Reads the real time clock and
returns time and other data stored
LCDwrite ()
Setup()
RTCwrite()
Write data to LCD
Runs sequence to set-up observing
session
Writes the real time clock and
returns time and other data stored
iRA holds the number of steps to step in RA
iDEC holds the number of steps to step in DEC
aOBJECTS((4,3) array that holds relative RA/DFEC and name for the 4
objects (VAR, COMP, CHK, SKY)
aRESULTS(~,4) holds the results for each measurement for each object
iCLOUD is a counter that is set to a figure and decrements when loud is
discovered, when it reaches zero a spiral search is initiated to look for
the star
The main program is executed by clock() interrupt (this is probably less processor hungry
than mindlessly looping).
The main sub routine (measure()) checks if there is a positive or negative value in RA or
DEC variables and if so steps the RA and DEC motors appropriately, incrementing or
decrementing these variables accordingly with each step.
Another interrupt increments the RA variable periodically to provide an RA drive feed.
To move to an object the main sub calls moveToObject this adds the relative number of
steps to the RA and DEC variable and so triggers movement to the object, all the time the
clockDrive interrupt is continuing to increment the RA variable at a rate to drive at
sidereal rate.
function
Sub-routine
interrupt
Other considerations
• I have no idea of how fast the APT can slew,
but we could think about having an observing
list that the telescope could work through