Electronic – Can i send a reset signal through the serial port

modemportrs232serialuart

I want to send a signal through the serial port to restart a modem, enfora gsm1218
(see datasheet http://www.testech-elect.com/enfora/pdf/GSM1218HR.pdf) is it possible?

I know that an AT command like AT$RESET exists to reset the software configuration, but I would like to hardware reset the modem itself as opposed to a software reset.

Best Answer

I have implemented this kind of thing using the modem control signals. You can wire DTR or RTS to a circuit that drives the RESET line of the system. Naturally you have to make sure your serial communications software isn't going to use those signals, or rather is prevented from controlling those signals until you want the desired reset to occur.

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Electronic – Is it possible to send characters through serial to go up a line on the console window

Use VT100 escape codes to control the cursor.

Eg.

puts("\033[2J");   // clear screen
puts("\033[0;0H"); // set cursor to 0,0
puts("\033[10B");  // move cursor down 10 lines
puts("\033[5A");  // move cursor up 5 lines

Electronic – does a serial port have enough power to drive a comparator circuit

Your circuit as drawn won't work properly, at least not with an RS232 serial port. The RTS and CTS signals are bipolar with respect to ground, and are expected to meet RS232 levels.

If the RTS line goes low, it will go negative with respect to ground and play tug-of-war with the LM339's ESD protection diodes. You'd also need to handle the case where the RTS line stays high (positive) but the comparator needs to provide a negative voltage on CTS, and therefore there's no guaranteed source of negative voltage, meaning you need to have a positive-to-negative voltage converter.

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Electronic – Is it possible to send characters through serial to go up a line on the console window

Electronic – does a serial port have enough power to drive a comparator circuit

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