bwack / C64-Saver-bwack

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A signal is interfering with the RESET pin #10

Closed bwack closed 6 years ago

bwack commented 6 years ago

When voltage is brought down below the threshold, the display stops updating.

OVERVOLTAGE is connected to the #RESET input of the MCU. We need the reset for the ISP to work. Here is a workaround: voltagedivider + adc !

https://electronics.stackexchange.com/questions/195146/use-the-reset-pin-on-attiny85-as-input-with-voltage-divider

addon board 1.0

bwack commented 6 years ago

I have inserted the voltage divider and the display is running in both overvoltage and normal conditions. I can't test the adc value at this point because I have joined 5V and 9VAC together, making the MCP1700 hit the dropout voltage if I try going under the threshold voltage. It shows that the voltage drops further when the state changes though.. So I'm happy with that for now. Programming is still working after change. Currently I have disconnected I2C traces SDA and SCL from U2 because it looked like it interfered with programming when using the minipro. Using an Arduino as ISP now. Will try reconnecting the I2C traces and see if programming still works.

bwack commented 6 years ago

I hooked SDA back up, and programming works, but the display shows garbage if the programming header and power supply is on at the same time. running the addon board from one or the other alone works fine.

bwack commented 6 years ago

connected SCL back, works fine. Programming and program.

bwack commented 6 years ago

connected SENSE_VAC back onto MISO. Still working fine. I conclude that the OVERVOLTAGE signal connected to the RESET input was the one that interefered with programming.

bwack commented 6 years ago

This issue is closed because it has been fixed in addon board v1.1, but in v1.0 here is information on how it needs to be modded:

without components: