Hello!
I'm pretty new to the Teensy ecosystem, but, even if my impression is that it's not the right board for the task, i'd really really love to use it for interfacing with the expansion port of the commodore 64. I got my Teensy 4.1 working as a disk drive, but had to switch to stm32 for the expansion port, mainly for two reasons:
- Voltages: all signals from the C64 are 5V, and the clock frequency is 1Mhz, although many signals switch at half that frequency.
- Pin count: Interfacing with the address+data buses requires 16+8 pins , plus around 10 more for control signals, and then 6-8 more for SPI / utility buttons, etc.
The disk drive emulation required just a few pins and level converters (thru-hole boards with 4 converters), but i thought scaling that to that many pins would be a bit overkill.
Right now i'm using a stm32h7 based board, which addresses both issues without needing external components, but it has problems of its own (specially, very slow GPIO), and it's a bit at the limit.I'd really love to use the Teensy, but i dont see an easy way to solve both problems (given that i want to use as few external components as possible).
Still, if i were to lift that restriction about external components, what components would you recommend for this project, given that time between reading and writing a bus/signal (mostly with low processing overhead), should ideally be in the 250-300ns?
I'm pretty new to the Teensy ecosystem, but, even if my impression is that it's not the right board for the task, i'd really really love to use it for interfacing with the expansion port of the commodore 64. I got my Teensy 4.1 working as a disk drive, but had to switch to stm32 for the expansion port, mainly for two reasons:
- Voltages: all signals from the C64 are 5V, and the clock frequency is 1Mhz, although many signals switch at half that frequency.
- Pin count: Interfacing with the address+data buses requires 16+8 pins , plus around 10 more for control signals, and then 6-8 more for SPI / utility buttons, etc.
The disk drive emulation required just a few pins and level converters (thru-hole boards with 4 converters), but i thought scaling that to that many pins would be a bit overkill.
Right now i'm using a stm32h7 based board, which addresses both issues without needing external components, but it has problems of its own (specially, very slow GPIO), and it's a bit at the limit.I'd really love to use the Teensy, but i dont see an easy way to solve both problems (given that i want to use as few external components as possible).
Still, if i were to lift that restriction about external components, what components would you recommend for this project, given that time between reading and writing a bus/signal (mostly with low processing overhead), should ideally be in the 250-300ns?
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