Some confusion there I think... The M100's serial port is in fact 'true' RS232; the official spec is +/- 3-15V and the M100's +/- 5V is well within that spec.
But today most hobbyist 'RS232' serial devices are intended to interface directly to a microprocessor of some kind, so they use 'TTL' RS232 which is 0 to Vcc (5V or 3.3V) (with the opposite polarity). https://www.sparkfun.com/tutorials/215 0 to 5V would probably indeed 'not make it' connected to the serial port on your M100 since 0V is in the undefined region between +3V and -3V and it's 'upside down, but connecting internally should be straight forward since the M100 is 'TTL RS232' internally (although you'd still need to shift the voltage levels from 3.3 to 5V). Aside from that I see no reason why the Pinenut module would not work; presumably you could even patch the ROM to change the 'M' default baud rate etc. I've been meaning to do the same thing with a BT module instead of WiFi but just reaching for an external RS232-BT module is just sooo convenient.. m From: jonathan.y...@telia.com To: m...@bitchin100.com Sent: Saturday, December 17, 2022 9:39 AM Subject: Re: [M100] Pinenut Wifi / BLE Hello, I'm not sure that thing will hook up to a real RS-232. I looked at the schematic and it talked about 3.3 v, which would not drive the RS-232 lines. Not sure how you would connect it. But maybe there is a level shifter in it. I've found that a lot of things talk about RS 232 but it is things like 0 to 3.3 or 0 to 5 volts, and not even close to real RS 232. I know the M100 doesn't actually get there either, but I know 0 to 5 volts doesn't make it on my M100. I had been looking at this device, in part for a Psion 5 MX but it also for my M100 as well. A 'hat' stuck on top of a Raspberry Pi zero W, plus a power supply. Admittedly most of the work would be done by the Pi (the tcp/ip stack etc.) but you could use a terminal program to access a little linux box. It was self-contained, even with a battery!! I still have to figure out where to buy that level-shifter (the SP3232EEP) but most hats I've looked at for the pi zero w don't have hardware handshaking. https://www.kianryan.co.uk/2022-11-28-psion-sidecar-ppp-modem-and-terminal/ Admittedly, this is probably to big to fit in an M100 but I am pretty sure it would work. Increase the size of the battery and power the M100 with it!! Jonathan ----Original Message---- From : hira...@hotmail.com Date : 2022-12-17 - 15:16 (CEST) To : m100@lists.bitchin100.com Subject : [M100] Pinenut Wifi / BLE I came across this tiny little board on the Pine64 site, and I wonder... PineNut Wifi/BLE board this thing is about 1" by 2/3" (25 x 14mm), and as I understand it provides wifi and bluetooth, via serial (TTL or UART, I think). I think it could be mounted internally to the M100 (dunno about M102). Maybe a 200, too. IF one could connect it to the modem serial connection, one could then theoretically use it to connect via wifi/bluetooth, and switch to the external rs232 port, keeping its functionality, with a minimum of "destruction" to the M100. Or maybe, connect it to the barcode scanner, which, if possible for regular comms with the module, would leave you able to use the rs232 and the wifi at the same time. I'm interested in any opinions on this, because imo it could massively improve the functionality of the M100 (yes, I know the same essential thing is possible with some of the wifi-capable arduino boards, but all I've seen of them are much larger than this).
