From: Jim Brain (brain_at_jbrain.com)
Date: 2004-10-23 22:42:03
Just a short note... Hársfalvi is my lastname... so, just in case you intended to call me by my firstname, you should call me "Levente" ;-). Many apologies. The last_name first_name thing is hard to discern from context. > The 10 cycles delay is introduced by the 10k resistor. I used it > mainly for safety reasons and compatibility (the 1351 had 5.1k, but > due to the 5717's outputs having greater resistance than the PIC16c84 > outputs, I raised it to 10k to meet similar delay in overall). Though, > I haven't investigated this further. In theory, you could completely > omit the resistor; after that move, the minimum value (read from the > SID registers) is a function of I tried that last night, but if the resistance is < 3k, the uController's ability to source is more powerful than the SID's ability to sink, so no falling edge is seen, so the unit does not work. However, at 3k, I can get down to "4". > Actually, you could use the Atmega8's internal RC oscillator (in case > you're experimenting with a 'mega8 ). I have one here, but was using a 16 for initial tests. However, I'll try the 8 I have. > The biggest problem -- if I'm correct -- won't be the protocol itself, > but the interference with keyboard activity. ...But I may as well be > wrong in this. My protocol idea assumes you don't scan the keyboard rows during the time you request raw data. Jim -- Jim Brain, Brain Innovations firstname.lastname@example.org http://www.jbrain.com Dabbling in WWW, Embedded Systems, Old CBM computers, and Good Times! Message was sent through the cbm-hackers mailing list
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