Serial Port

Hawk

Has anyone tried connecting a serial port to a EB NG board?
The commands to drive it appear in the Reference Manual, however it looks like Uli is planning to remove them.
I have an old serial pen plotter that I thought it might be fun to connect.
I guess to connect it I'd need a Max232 level converter chip to convert from TTL serial to RS-232 serial.

painintheworld

That is a good idea, Hawk. It would epic (useless, sure, but still epic 🙂 ) to connect my original Atari 1020 plotter to a BENG.

Hawk

painintheworld OK, I've ordered the part. I should be able to give this a go some time in March! 😆

Hawk

Just doing some pre-reading again. The serial port is supported by the commands:

SMODE
SWRITE
SREAD (useless)
SREADY (useless)

Does the SWRITE function block if the receiver is unable to receive?
Otherwise, I can see that I would have to manually write a function to implement XON/XOFF protocol, since there are no control lines allocated. (The hardware that I've ordered also doesn't support hardware control, only Tx/Rx).

Looks like I'm going to learn about XON/XOFF.

Update: OK, that was quick...doesn't look like I can implement XON/XOFF, as I can't read serial bytes.

@uli , are there other UARTs that are available to use for serial, other than the one attached to the audio out?

uli

The contention between audio and serial port does not apply to the NG platform. That's all of the good news, however, because the serial port commands are not wired up there ATM...

Rather than fixing that, however, I think I'm just going to drop these commands, because I have just yesterday realized that on the soon-to-be-almost-in-prototype-stage Linux-based system, you can simply do OPEN "/dev/ttyS<something>" FOR [OUTPUT|INPUT] AS #1 and use the standard file I/O infrastructure. Really nifty, I dare say. You will also be able to use UART 1-3 on the expansion connector, and will probably want to do so because UART0 is used for the serial console.

Hawk

Sounds good @uli . By the time my H/W arrives you'll probably have the new update ready.
Do you know if the flow control is handled by the UART, or do you have to implement that yourself?

painintheworld

This would be so cool to interface with the PLATO type system at [https://irata.online/](https://) , or other BBS type system. I'd love to run a BBS that was getting traffic from a BASIC Engine, Color Maximite, and similar devices.

Hawk

Ok @uli , the freight company were extra quick, and my TTL to RS-232 serial converters have arrived already. I'm keen to give them a whirl. ;^)

Oo...I just had a horrible thought. Am I going to need level converters for the H3 to TTL?