Steps to read data from ARM microcontroller port

Question

I am having trouble reading serial data from ARM LPC2378 microcontroller. Will I have to use UART or any GPIO port can be used?? is ayone having c code for it??

Answer 1

It is technically possible to use a GPIO port, but then your software is responsible for bit timing, framing, error checking etc. It's often called "bit-banging" since your code has to do every bit, and so it's CPU intensive. For lower data rates, you could run it from a timer interrupt.

Using a UART is much easier—the UART does the hard work of bit timing, framing, error checking, etc.

According to the LPC2378 data sheet, the microcontroller has 4 UARTs. So using a UART is the way to go. What pin is your serial data coming in on? The serial data has to be connected to a pin that can connect to one of the 4 UARTs. You will have to set some registers on the microcontroller to set it up for UART usage:

• Enable the UART, and its settings (lots of settings there)
• Set which pin is the input for the UART (maybe)
• Some other pin settings

At first, you can try polling the UART—read its "RX byte available" flag until it says "there is a byte available", then read the byte from the received-byte register. Also read the RX error flags register to see if there are any errors.

After that's working, you can work on getting RX interrupts working, so a receive interrupt is generated to handle incoming data.

This sort of thing requires some reading time in the user manual and datasheet. Enjoy!