Please help I have a 8 bit micro connected to the UART1 of the modem (3v3 levels)
I got the following info off the modem that has the CTS problem
Q:0 V:1 S0:000 S2:043 S3:013 S4:010 S5:008
+CR:0 +CRC:1 +CMEE:1 +CBST:0,0,1
+SPEAKER:1 +ECHO:0 &C:1 &D:2 %C:0
+IPR:115200 +ICF:3,4 +IFC:2,2
R73a00gg.Q2687G 2094168 032009 12:40
The problem with the MODEMS is related to the CST/RST handshaking between the modem and the Micro.
Procedure is as follow:
RTS is toggled and then CTS is suppose to be asserted, the software checks for the CTS line before it continues to issue at commands.
Herein lies the problem on a particular batch of modems the CTS (ClearToSend) signal is not asserted by the MODEM.
If I replace the modem with a version Q2687H and old V6.6 firmware it works but Q2687G CTS does not work.