Greetings All, Can anyone direct me to information on connecting a Hayes type external modem to a Motorola '705 controller?
Microcontroller w/ Modem
Mar 21, 2005
2 Replies
By using the phrase "Hayes protocol" in a Google search I found that there are some reasonable links in the first page 1 to 10 of 290,000 or so.
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At a minimum you would need a UART (Serial controller on MCU) with Rx and Tx plus a EIA-232 Buffer. Something like a MAX232A or any of the hundreds if not thousands of similar ICs. You then need to set the modem to use no flow control or Xon/Xoff flow control and to provide the normal status info such as Carrier Detect over the serial link. If the specific version of '705 you are using does not have a UART, then you can bit-bang for low baud rates.
Regards Anton Erasmus
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