RS232 with flow control.

[tavioman]

Hi all. I'll probably be a little off topic. My apologies for that.
I want to know in what state the pins RTS and CTS are active.
Let's assume my MCU is DTE.
DCE waits for RTS till data can be send to DTE.
Now, I will tie the pin low or high for DCE to send data?

[Humberto]

For RS232 Data and Control signals:
-a HIGH level in the TTL side correspond to negative level voltages in RS232 side.
-a LOW level in the TTL side correspond to positive level voltages in RS232 side.

Yes, it is quite confusing but general speaking, to activate a Control signal -in TTL side-
you should pull it down (LOW).

http://www.ccsinfo.com/forum/viewtopic.php?t=24612&highlight=handshaking


Humberto

[tavioman_]

Hi Humberto.
I'm using I'm using CMOS MCU( PIC ) to comunicate with GM862 GSM module that is also a cmos. I'm not using a GSM terminal.
What you said above still aplies?

[Humberto]

I had been looking for such devices. I found the GM862 Module wich use the Telit Unified AT
Command Set, if this is the module you are using, it should be handled like a DCE modem.


Humberto