Hi dc42, Thank you very much for your reply, its very helpful!
The 100 ohm resistors, are for protecting the input pins, in case they are accidentally configures as outputs, but it seems a bit “clumsy”, and I’ll go for the more usual approach with pullup resistors.
I already have the IRL1404 mosfets, so I’ll probably try my luck with them. I’ll be using some very large heatsinks scavenged from an electric forklift.
Setting the PWM frequency to about 20 khz should be possible for timer1, but I’ll have to read up on that. There are already a couple of threads on this forum on the subject, but it’s hard to understand.
I’m now thinking of using these for flyback diodes: http://www.sanrex.com/images/PDFs/BKR400AB10.pdf , but I can’t make out if they are fast enough. Would it be a good choice? Or can anyone suggest an appropriate diode?
I have some more questions regarding noise suppression.
What kind of capacitors should I use for motor noise suppression?
I’m planning of using the mower chassis for common ground (like most cars). Is that a bad idea?