Sharing Max232 with two pics?

[Bruce]

Why not just use one of the OPEN baud modes? This leaves the TX pin set to input
after the transmission is complete.

[zx81sp]

Why not just use one of the OPEN baud modes? This leaves the TX pin set to input
after the transmission is complete.

With OPEN transmission does not works, nothing happens, I think that mode is for direct connection to the PC.

I'v solved the mistery of the broken PICs (just a programmer bug), anyway if someone have a better idea to share the MAX233, would be appreciated.

Thks

[mister_e]

OPEN mode work if you use a good enough pull-up resistor for true mode...

[zx81sp]

OPEN mode work if you use a good enough pull-up resistor for true mode...

I can try it, would be enough a 47k resistor?

[Bruce]

47k may work, but 4.7k to 10k will for sure.

[zx81sp]

Something does not works

I'm testing with another board, just a 16F628A 20mhz OSC and a MAX233 that sends 'D00000' or 'D11111' every time RB.4 changes, it works ok if I use True Mode T9600 (RB.5 connect directly to MAX233).

Try to change it to Normal Mode (N9600) modifying the board (a resistor between +5V and RB.5), but the PC receive trash:

p}ŸŸŸŸWÖÖÖÖp}ŸŸŸŸWÖÖÖÖp}ŸŸŸŸ

I've tried with several resitors (47K, 10K, 7.2K, 2.7K) with no difference.

What I'm doing wrong?

[Bruce]

What I'm doing wrong?

Trying to use inverted mode when you should be using non-inverted or TRUE mode.

You have to use TRUE mode when going through the MAX232.