desertrout
Well-known member
Hey! I'm hoping someone is willing to share some insights for an issue I'm hitting with an internal PB 1xx NodeMCU (8266) wifi modem emulator board I'm fussing with... whenever the board is powered and connected internally, the PB acts possessed.
I've got a pcb with the ESP, max3232 and necessary caps, and the connector fitted - fits great in the internal modem header. The board works properly when powered externally and connected to the external modem port from my PCB's connector, so I know Rx, Tx, and GND are wired up properly for a basic three-wire hookup. Great!
However, things get weird when installed internally. Here's what I can tell you:
- I bridged /MODEM.INSERT and GND, and the board is being detected because I can choose the internal modem from the Powerbook control panel when it's installed (vs no option when it or any other modem is installed)
- I do have the 10k resistor between MODEM.PWR and MODEM.5V (now that read the relevant part of the 'Designing Cards...' docs, lol. Link, pp.502-515: https://vintageapple.org/inside_o/p...for_the_Macintosh_Family_3rd_Edition_1992.pdf )... and the card does power up when I load something like ZTerm
- If the card is powered externally via the NodeMCU's USB jack or directly from US5V on J8, the PB itself starts acting up - it's like it starts messing with trackball signals, where Finder windows scroll to the top and items are seemingly randomly selected
- If the card is powered internally (via MODEM.5V), it still acts up but obviously only after powering up... but by this time I have ZTerm open and it's sending a constant stream of nonsense data to the terminal window... even though the settings are exactly the same as when it was being connected to the external modem port and was working properly...
I do have some additional things to try after looking at https://subethasoftware.com/2018/02...-under-10-using-esp8266-and-zimodem-firmware/ -- and I will keep digging into RS232 literature (I'm just figuring this out as I go), but if anyone has a hint as to what possibly could be happening here I'd love to hear it.
I've got a pcb with the ESP, max3232 and necessary caps, and the connector fitted - fits great in the internal modem header. The board works properly when powered externally and connected to the external modem port from my PCB's connector, so I know Rx, Tx, and GND are wired up properly for a basic three-wire hookup. Great!
However, things get weird when installed internally. Here's what I can tell you:
- I bridged /MODEM.INSERT and GND, and the board is being detected because I can choose the internal modem from the Powerbook control panel when it's installed (vs no option when it or any other modem is installed)
- I do have the 10k resistor between MODEM.PWR and MODEM.5V (now that read the relevant part of the 'Designing Cards...' docs, lol. Link, pp.502-515: https://vintageapple.org/inside_o/p...for_the_Macintosh_Family_3rd_Edition_1992.pdf )... and the card does power up when I load something like ZTerm
- If the card is powered externally via the NodeMCU's USB jack or directly from US5V on J8, the PB itself starts acting up - it's like it starts messing with trackball signals, where Finder windows scroll to the top and items are seemingly randomly selected
- If the card is powered internally (via MODEM.5V), it still acts up but obviously only after powering up... but by this time I have ZTerm open and it's sending a constant stream of nonsense data to the terminal window... even though the settings are exactly the same as when it was being connected to the external modem port and was working properly...
I do have some additional things to try after looking at https://subethasoftware.com/2018/02...-under-10-using-esp8266-and-zimodem-firmware/ -- and I will keep digging into RS232 literature (I'm just figuring this out as I go), but if anyone has a hint as to what possibly could be happening here I'd love to hear it.