Started by CraigsBar, 16:24, 17 January 21
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Quote from: Bryce on 16:46, 17 January 21Yeah, easy, just put a button between pin 26 of the CPU and GND.Bryce.
Quote from: CraigsBar on 17:07, 17 January 21I was hoping it would be that easy... So glad you did not mention the ASIC!
Quote from: Bryce on 17:23, 17 January 21If it's "fat-fingered soldering" that you're worried about, remove the CPU before you solder. There's also a diode (D202) that goes to Pin 26 and you could solder the button to that point instead (the Cathode of the diode).Bryce.
Quote from: Bryce on 19:40, 17 January 21That is the BUS reset of the GX4000. There is no other reset.Bryce.
Quote from: CraigsBar on 22:24, 17 January 21OK. So I trusted continuity from asic 159 and resistor r17. Its a direct connection. Did the same on my plus (pin 159 and BRST on the expansion port) also a direct connection.Tested with a patch cable. This reset r17 (asic side) to ground works perfectly. Adjusted the soldering to move the cable to these points rather than the bottom of the board. 100% success. GX4000 reset button works perfectly on BRST from the asic.
Quote from: rewk on 14:19, 23 July 21Hi, I'm also trying to add a reset button.Wouldn't this create a short between +5v and the ground ? It seems the GX4000 lacks a 2.2K resistor between the BRST and +5v, like the 6128plus.Would it also work with the C4CPC ? My guess is that the microcontroller on it won't be reset, and won't go back to the cartridge selection menu...
Quote from: CraigsBar on 15:50, 23 July 21The button goes between BSRT on the ASIC and Ground not +5v this is the exact same connection as is used on the BusReset on the expansion port of the 464+ and 6128+ and it behaves in the same way. so no it unfortunately does not reset the C4CPC, that still needs a power cycle.
Quote from: rewk on 16:52, 23 July 21On the GX4000, there is no such resistor and the BRST is directly connected to 5V. Which means that bringing it to low would short.Or am i missing something ?
Quote from: gerald on 20:17, 23 July 21Early C4CPC (90% of the 1st batch) does not see the reset. There is no direct way of getting the reset. On the later version, I've implemented a system in the PLD that detect it indirectly through the ACID signals. But this does not reset the microcontroller either, just inform it that the CPC has reset. By default, the CPC just ignore it so when you use the system cartridge it will reboot immediately. Only CprSelect takes advantage of it and is reloaded on a reset. I can update your card if you want, but for that you have to ship it back to me
Quote from: CraigsBar on 20:33, 23 July 21 oh hell yes please. Can you update Both of them! I have 2 you see.
Quote from: gerald on 20:08, 23 July 21On my development GX, I do that by shorting the the common node of R17, R90 and D10 to GND.
Quote from: gerald on 20:17, 23 July 21There is no direct way of getting the reset
Quote from: gerald on 20:17, 23 July 21I can update your card if you want, but for that you have to ship it back to me
Quote from: rewk on 11:53, 24 July 21Sometimes, the reset is not really complete and the C4CPC displays a bit of garbage in the path area, or sometimes it doesn't detects the reset, but overall, it works really well!
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