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Search - "rs-232"
I made a program that dispenses coins in 345 lines. It tells you if the coin tray is in place, and if it didn't dispense enough coins it will tell you how many successfully dispensed. It also has ACK\NAK communication. It's written in C for a specialized microcontroller.
I have written code that talks to 4 devices, but this is the only one I have written the code for. In 2 years it has never had a bug, and always responds quickly and correctly via RS 232.
Operation PiBM 5150 XT is continuing this morning!
Raspberry Pi B+ 900mhz
Raspbian Pixel Linux
LG 21:9 2560x1080 monitor
/boot/config.txt updated for 21:9 monitor
Nyko PS3 USB Compact Flash / SD Reader
4gb CF card as HDD in 5150
4.77mhz IBM 5150 in like new condition
CGA Graphics and Monitor
Late 2012 Macbook Pro
USB to DB/25 (RS-232) serial adapter
Because old hardware means learning the hard way sometimes, I've had to purchase more goodies.
On my last update, I installed the rs232 shield which may have inadvertently been wired backwards for Tx/Rx from what im used to. I assume it is backwards to most db9 serial ports because most Arduino or other projects you would do with a pi have serial "in" connections like old routers and devices that would be "controlled" rather than the other way around. Anyway, according to a video on youtube showing a guy turning an old machine into an IRC client via raspberry pi, this shield may be swapped. That means that instead of interfacing with the old machine via a null modem crossover cable, I need a straight cable with male db9 on both ends. I unfortunately tried using the null modem crossover cable which was reversing the reversed pins all over again. I hope these next few days are more fruitful now that I've bought a straight cable and db9/25 adapter.
The good thing is that I managed to get the pi to recognize its new serial port. I also dusted off my DOS skills and my serial card in the 5150 seems to work.
I literally banged my head after nothing worked. Im hoping that the tx/ Rx is solved soon.
Oh and that AT to PS/2 adapter will allow me to use by IBM original Model M Keyboarf rather than the fun model F.
I told you guys that I would update you on my PiBM-5150 project. I figured out the hard way that my USB to DB-25 cable wouldn't cut it. Seems it is for printers and no matter how hard I tried it wouldn't work because of the path of the wires. After researching, it is apparent that the GPIO pins on the pi are configured for serial by default but it requires a little voltage change from TTY to RS-232. Rather than do like one of the videos I saw and solder junk to a bread board, I found a serial (rs-232) shield and 9pin output for the pi. Now, both computers are true rs-232 each. Instead of using a modem between them, I bought a null modem cable (crossover of Tx Rx signals) to interface the two machines directly. I'll update this evening to show it hopefully working.