The Joy of Bit-Banging

You might be interested in this talk: http://lwn.net/SubscriberLink/515569/aab5102c0daa0f5d/

I am really tempted to get it. I have a $390 LogicPort [0] which is a 34 channel, 500 MHz probe (quite a bit beefier than the Logic's 8 channel, 24 MHz). The hardware is great but the software is rather terrible. There is no way to add your own protocol decoders. Export features are limited. I wanted to write my own GUI so I contacted the company and asked if they had any documentation on the USB protocol. Their response was snarky and rude. Sad, because I really wanted a Linux version. Maybe reversing the protocol wouldn't be too difficult...

[0]: http://www.pctestinstruments.com/

Absolutely. One of the guys here at HP got one and within weeks our group owned half a dozen. No reason not to have one in each cube. I have an expensive mixed-signal scope that I used for LA before but now only switch it on if I have to look at analog.

Thanks.

Recently I had to bitbang I2C through a voltage level translating buffer that had a direction setting pin that needed to be manipulated when sampling SDA on input. The uC's hardware I2C block obviously couldn't handle that extra signaling oddity. Not the fastest approach but then this I2C application wasn't that high speed to begin with. Good times indeed!

... and often the specialised hw doesn't go far enough. ie- i2c and spi hw that doesn't have enough buffering to be left on its own. Either we babysit the interface or we can leave it to do its own thing until we get an interrupt for completion. Do a halfway job on the hw and we revert to the babysit case. Not bitter, just ranting.