RTS/CTS flow control for comms with GSM modem

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#1
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Hello there,

I want to connect an ATmega162 with a sony-ericsson GM29 GSM modem(AVR as DTE). The problem is that the modem has hardware flow control on its RS232 port enabled by default, and I have trouble implementing hardware flow control an the AVR side. What I have tried so far is pulling the RTS line low, and wait CTS line (connected to INT0) to trigger an interrupt. Then allow the program to send a byte and pull RTS line high again. Is this right? Any help would be greatly appreciated.

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The Nut/OS AVR uart-driver is a good source of information how to implement RTS/CTS flow-control with an AVR.

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I have a more precise question. It makes any difference if the RTS signal is held low just until I get the CTS responce or until the whole frame is being transmitted? Any help would be greatly appreciated. I can't find a timing diagramm anywhere.

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Problem solved. I may post this in the academy section when I will find time.