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Re: Bad characters while communication over serial port

 by pavanvd ¦  Fri Sep 21, 2018 9:05 am ¦  Forum: Projects ¦  Topic: Bad characters while communication over serial port ¦  Replies: 2 ¦  Views: 234

the "real" serial port on Pi3 is set by default to communicate to the on-board bluetooth. Make sure to disable. There are many articles around that e.g. see https://spellfoundry.com/2016/05/29/configuring-gpio-serial-port-raspbian-jessie-including-pi-3/ regards, Paul Hi Paul, Thanks for the respons...

Bad characters while communication over serial port

 by pavanvd ¦  Thu Sep 20, 2018 5:04 am ¦  Forum: Projects ¦  Topic: Bad characters while communication over serial port ¦  Replies: 2 ¦  Views: 234

Hello All, I am interfacing a SIM800 GSM module with Pi 3 over serial ports (pins 6, 8, 10). While things work OK most of the time, every now and then I get spurious characters in the response. For example, I get: ['+CLCC: 1,0,2,0,0,"+919812x\x9c\xd3\x13\x93\x93\x12)\xa25,""', 'OK'] whereas the expe...

Re: Speaker and microphone for GSM module

 by pavanvd ¦  Sun May 14, 2017 8:02 am ¦  Forum: Projects ¦  Topic: Speaker and microphone for GSM module ¦  Replies: 6 ¦  Views: 2357

The PAM8302 chip seems functionally equivalent as the Sparkfun amplifier has. So yes, I guess so. Adafruit sells a similar amplifier board based on that chip. I don't know about the LM386 or what is required for them to be honest. Never played around with those although they seem to be pretty popul...

Re: Speaker and microphone for GSM module

 by pavanvd ¦  Thu May 11, 2017 11:50 am ¦  Forum: Projects ¦  Topic: Speaker and microphone for GSM module ¦  Replies: 6 ¦  Views: 2357

Ok, I couldn't find an explanation of the pins on the board. Or a datasheet for it. If it does have analog audio out then it is probably only line-out level (1 volt peak-peak I think) You'll need an amplifier for that. This should suffice to get enough volume out of that speaker: https://www.sparkf...

Re: Speaker and microphone for GSM module

 by pavanvd ¦  Thu May 11, 2017 11:27 am ¦  Forum: Projects ¦  Topic: Speaker and microphone for GSM module ¦  Replies: 6 ¦  Views: 2357

Thanks for the reply. The TTL UART part is to interface with the micro controller, right? For example, I have connected Pi's TX/RX pins to the respective RX/TX pins of the modem and sending AT commands using a python serial terminal. But there are separate pins to get audio out and mic in. Otherwise...

Speaker and microphone for GSM module

 by pavanvd ¦  Thu May 11, 2017 10:47 am ¦  Forum: Projects ¦  Topic: Speaker and microphone for GSM module ¦  Replies: 6 ¦  Views: 2357

Hello All, I'm a newbie to electronics, so pardon my possible naive questions. I am doing a project for fun and have successfully interfaced a SIM900 based GSM modem with a Pi. Using specific AT commands I can send/receive SMSes and also initiate and receive calls. But I am now trying to get audio i...