Help! DIY 4 amp L297/6203 driver

[irving2008]

Well lets think this through...

Whats the slowest meaningful step rate, 1 step/second? how long after the last step do we want to wait, 10 seconds?

So every time there is a clock pulse, reload an 'n' second counter. when the counter reaches 0 start a PWM output with a frequency of 100Hz say, and a mark/space ratio controlled from 2 dip switches giving 100 (off), 75, 50 and 25 settings

Use a couple more DIP switches to set the initial delay 'n', say 20, 10, 5, 2 seconds.

Pseudocode:

Interrupt routines:
If INT0 (external)

read delay value
reset main counter to delay value
set PWM output high (open collector)
reset INT0
return

If INT1 (main counter reached 0)

read PWM value
initialise PWN registers
start PWM running
reset INT1
return

Main program:

set PWM frequency
set PWM output high
configure counter clock divider
configure INT0 on external trailing edge
configure INT1 on counter timeout
read delay value
reset main counter to delay value
enable INT0
enable INT1
halt

obviously, depending on the chip used you may have to synthesise the PWM function with counters and a lookup table to determine the correct counts for each DIP setting.

[Ross77]

I wont pretend to understand that, but it looks impressive, cheers

Any tips for laying out pcbs in Eagle or is it practice makes perfect? this could take a while.....

[graffian]

er the ones that always hits me, repeatedly, I am not learning. Everything looks much smaller when it's actually on a pcb, smaller than the screen that is. So those neat narrow little traces and tiny pads are even smaller than you thought. oh and make the holes in the pads very small as large ones make soldering not as neat and the drill won't center aswell. Well those are things I need to remember, but don't till I am looking at the laser print.

I seem to remember Mariss from Gecko offering to sell cplds programmed pretty much as in the geckodrives, for something like $5 a time?
It was mentioned in the looooong thread about the Alegro A3986 chip that everyone decided didn't work properly, this is on CNC zone. That must be worth a look.