pwm 18f2431

[robertpeach]

thanks for the reply,

yeah i want to use the motion feedback module since its obvious there will be advantages using it (otherwise it would have been pointless to create). its just im a bit sketchy with how i would go about that. the motion feedback module actually continuously measures the pulse width of the input signal, so that would run in the "background" and within my code, i would create interupts that would jump to cap1 and that would give me the pwm (that it was automatically measuring) at that moment in time. and then i can temporarily save that pwm and use it for my algorithms etc. so before the START of my program i would have had to set my cap1 cap2 cap3 all to be measuring the the pwm? (using the assembley code commands to take advantage of its special features)

[robertpeach]

i realise probably the reason noone has posted is because not many ppl have used the 18f2431, but any help at all would be beneficial to me. i kinda seem to have met a dead end with it...

edit: after more digging, ive been looking into a program for interupts created by darrel taylor that seems quite convincing. it has specific interupts for the motion feedback modules.

[mackrackit]

I think you are correct that not many have used this chip. I was hopping Bruce Or Darrel would reply to this. When I get a chance I will look at the data sheet.

DTs instant interrupts works well for what I have used it for so when the motion module is undrstood they should work well for that too.

Sorry I can not be more help at this time.

[robertpeach]

thanks mack

yeah i was looking at instant interupts aswell...

my coding is quite abysmal at this time, but the general idea is what im heading for at the moment till my coding is up to scratch (hopefully picbasic pro will actually arrive today :P including a manual that might actually help!)

CAP1M3:CAP1M0 = 0101 'capture channel 1 is measuring period
CAP1REN 'capture timer5 is reset after each measurment is made
CAP2M3:CAP2M0 = 0101 'capture channel 2 is measuring period
CAP2REN 'capture timer5 is reset after each measurement is made
CAP3M3:CAP3M0 = 0101 'capture channel 3 is measuring period
CAP3REN 'capture timer5 is reset after each measurement is made

(i realise its asm)

this is just the starting for actually capturing the result. this measures directly to a buffer for each channel without the need to save it with any coding. CAP1BUF, CAP2BUF and CAP3BUF. would it be possible to have this running in the background? and not actually create an interupt to get to it? since it is already saved automatically in a buffer. cant i just during my program just "read" from the specific buffer and not actually entangle myself with the measurement processes that are going on at the CAP's.

thanks

[mackrackit]

You do not need interrupts. You should be able to read it just as you would an ADC or other hardware things. The interrupt option is just that with hardware that might be helpful.

I will try to get a chance to read through the data sheet later. I have some of these chips on order now. So maybe in a week or so I will be asking you questions.

[robertpeach]

ok thanks mack

unfortunately i still dont understand much about these interupts and how they can help me, but ill keep searching around and looking at example codes.

haha ill be as much help as possible but dont expect much!

[robertpeach]

sorry again to post here, but since i dont actually have the program yet to play with since it hasnt arrived, i cant actually trial and error anything im doing... or any basic language im picking up.

one thing i am interested in is just reading values that would be saved at a certain filename. ive looked up the filenames in the datasheets etc..

to use my specific data value would i have to convert it to var? and then use it in my calculation algorithm.

READ F69H, w0.BYTE.o 'cap1 value written to word0 byte 0
READ F67H, W0.BYTE.1 'cap2 value written to word0 byte 1
READ F65H, W0.BYTE.2 'cap3 value written to word0 byte 2

is this an incorrect way of accessing my data? im sorry i cant actually test it myself as of yet...