Bit-Bang Serial (RS232) Output via Joystick Pin (PORTA-Bit 0)

[+mytek]

Other way around -- port A reads (input AND output) for outputs, while port B reads outputs. You can set port A to all outputs with output $FF and still read joystick port 1.

 

Wow! Really? That is just too cool. I'll have to give that a try.

 

Thanks,

 

- Michael

[_The Doctor__]

So how does this journey end and will it all be on weebly?

[+mytek]

24 minutes ago, _The Doctor__ said:

So how does this journey end and will it all be on weebly?

Wow a flash from the past

 

I think that journey ended a long time ago

[_The Doctor__]

I'm still holding my breathe for the documentation, finalized schematics, and software. It's just been 5 or so years and you were nearly done! Did you give phaerons suggestions a try? I just have to know

 

-=> Serial Ports are near and dear to old Sysops <=-

 

fun stuff.

[+mytek]

On 7/11/2021 at 4:56 PM, _The Doctor__ said:

I'm still holding my breathe for the documentation, finalized schematics, and software. It's just been 5 or so years and you were nearly done! Did you give phaerons suggestions a try? I just have to know

 

-=> Serial Ports are near and dear to old Sysops <=-

 

fun stuff.

No I moved on to another way (used the UART in a PIC chip), and never went any farther on this project via the Atari.

 

[_The Doctor__]

3 hours ago, mytek said:

No I moved on to another way (used the UART in a PIC chip), and never went any farther on this project via the Atari.

 

please do tell !!!   or point us to the uart serial pic project

[+mytek]

9 hours ago, _The Doctor__ said:

please do tell !!!   or point us to the uart serial pic project

This project was so long ago, and my brain refresh has gotten weak, so not much more I can say other than when I first got back into the A8, I was looking for justifications to use it in some of my 'normal' work. But the truth of the matter is it was far easier to just add some additional PIC code to a stepping motor device I was working on, and have it directly talk RS232 with my PC for control and data collection via Dasylab. So that's what I ended up doing. Really not much else to say about that

 

Anything related to serial I/O via bit-banging on the Atari I already covered in this thread.

 

However I did find the missing image of a simple TTL to RS232 level shifting circuit I used in the project.

 

 

For the transistors, a 2N2222 or 2N3904 works just fine for the NPN (BC547). And a 2N2907 or 2N3906 will substitute for the PNP (BC557).

 

EDIT: I only used the TXD half of the circuit in order to send data out from the Atari via a joystick pin.