IOIO gives wrong data from UART

[Bobi Zrncev]

Hi,

I am trying to connect IOIO to a GSM modem with UART. If I connect it to PC it gives the output "10 a1 02 00 00 5d 10 03" every 10 seconds. I managed to connect it to the IOIO but it gives the output "d7 d9 ff ff 45 df f9" every 10 seconds. What can be problem?

I connect to uart using: uart = ioio_.openUart(3, 4, 9600, Uart.Parity.NONE, Uart.StopBits.ONE);

public void loop() throws ConnectionLostException, InterruptedException {

    try {

        int availableBytes = in.available();

        if (availableBytes > 0) {

            try {

                Log.d("UART", "Received is " + in.read());

            }catch (IOException e) {

                e.printStackTrace();

            }

        }

    }

}

Best regards,

BZ

[Ytai Ben-Tsvi]

This smells like an electrical problem. What are the electrical specs of the modem? How exactly are you connecting it to the IOIO?

As an aside, your loop() doesn't block (i.e. spin-loops) whenever there is no data in the UART, which is a very bad practice (maxes out CPU, drains battery). You probably want to simply remove the "if" which would result on it blocking on the read() as much as needed.

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[Kevin Miller]

Hi BZ,

What PC interface/software are you using to read the data and display the "d7 d9 ff ff 45 df f9" output? Is it consistent? If so, it looks to me to be a settings error - baud rate, stop bits, etc. Did you verify the PC interface/software with a known good UART? Does your Interface support 3.3V? Since you are sending 8 bytes but only 7 bytes are displayed, my money's on the baud rate.

Hope it helps,

Kevin