LPC55S0x UART

[chiara_delfini]

Hi,

I have to implement a simple serial protocol on LPC5506.

I  would not use FIFOs because I have to send few (4 or 5) bytes at the time.

I saw that FIFO dimension is fixed to 16 bytes...

How have I to use the UART?

If I just write 1 byte in the FIFO, nothing happens...

Thanks for helping

Chiara

[chiara_delfini · Accepted solution]

Solved!

Thank you 
Chiara

[xiangjun_rong]

Hi,

Of course, you can disable the FIFO feature of Usart module for the LPC550x.

If you want to develop high efficient code, you can write register directly.

Hope it can help you

BR

XiangJun Rong

[scottm]

The FIFO size is fixed at 16 entries, but that doesn't mean you need to send in multiples of 16 bytes. If you're writing data to the FIFO and it's not being sent, the UART must be configured wrong. Make sure it's enabled in CFG, and check TXDIS in CTL. Verify that you have the clocking set up correctly.

I'd suggest starting with one of the MCUX SDK examples, even if you're not going to use the SDK in your project. But beware - NXP isn't very careful about testing and documenting their examples. It's common to find UART loopback examples that use a free-running oscillator as their clock source, for example. That's fine on the same board, but if you're connecting two boards their clocks might be out of spec. So while the example will almost certainly work, you should be cautious about applying it to your example.

Scott