[retired] [WIP] 20mm single sided & 17mm double-sided ?-amp linear driver - surprisingly good!

OK, I’ve implemented “bypass” on my stripboard. My test setup has a lot of resistance, but it does function properly with a high-drain cell.

In order for the bypass to function, code changes were required. Basically the normal ATtiny pin-output “off” state causes a problem when hooked up to the DRV/gate stuff. Therefore we cannot use the code Werner posted over here (post#61). Instead we must keep that pin in High Impedance mode, what Atmel calls “Tri-state” or “Hi-Z”. When we’re ready to do the bypass we then put the pin in Output High (Source) mode. Table 10-1 in the datasheet shows the register setup necessary.

I’m putting the proof-of-concept code here. Sorry my code sucks so bad, it’s just a proof-of-concept. It’s not intended to provide a usable interface. EDIT: hint - the bypass is only functional in v009.c. Earlier versions are me mucking around with testing levels and things or me figuring out how we needed the pin state setup.


Side note: I also noticed that the M6 actually uses a bank of 0805’s rather than 1206 sized resistors. In order to have the same power-handling capability you must spend twice as much on resistors, but it should allow more granular setting of current. (0805’s have 0.5W handling but cost the same as the 1206’s which have 1W handling.)


EDIT: The next step is to determine dropout voltage, but I think I’ll have to build the real driver for that testing to have any meaning.