Two years ago I built an alarm unit using the flash lab system with a 18F452 running at 20Mhz. It has been in the field on different construction sites since then and has worked flawlesly.
I have built a second one using the flash lab again but with a 18F452 running at 40Mhz. The only other change is the LCD was a 2x16 and now is a 4x40 serial LCD. The keypad the LCD the menue sytem all work as expected but I can not get the GSM modem to send the text messages, which makes the alarm useless.
Surely it can not be the change in chip speed that is causing the problem?
I have tried serin2 serout2, hserin hserout, I have put delays in the instructions and pauses in the program. I have checked and changed about every AT command on the modem and nothing changes.
I have used the LCD to debug the program and the PIC does not seem to be getting any replies from the modem, except the first one. I send AT to the modem the modem replies with OK and the program continues to the next instruction which also requires a reply from the modem and it just stops there.
I have connected to the flash lab with hyperterminal and when I type in the expected replies the program runs and when I use hyperterminal connected to the modem it works as expected. They just will not talk to each other.
???????
Steve
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