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FWIW you probably don't need a USB serial port, or a RS232 converter at all; you could just pick the TTL serial signals off the commodore port and plug them int
by a1k0n 10y ago
FWIW you probably don't need a USB serial port, or a RS232 converter at all; you could just pick the TTL serial signals off the commodore port and plug them into the TTL serial port on the Raspberry Pi 23- or 40-pin expansion slot (pins 8, 9, and 10 are TX, ground, and RX.). Remove the tty on /dev/ttyAMA0 from the init config and you can use /dev/ttyAMA0 as your built-in Pi serial port.
- jeff_harris 10y agoThanks, yeah, I will try this - I followed a design for a c64-pc cable without considering that the Pi probably had serial port pins.
- khedoros1 10y agoThe DC voltage supply on the Commodore side looks like 5V, and at a guess, the TTL probably runs at that voltage too. The Pi won't be happy with more than 3.3V on its UART pins, so the USB adapter also fills the purpose of a voltage adapter.
- a1k0n 10y agoRight. I thought it might be 5v tolerant on the RX pin but maybe not.. easy enough to just use a resistor and a diode to the 3.3v supply to level shift there, and the 3.3v TX should be fine for a 5v logic input.