UART break

[Sascha]

Hello together, i have a question to the uart hardware communication. I try to send 6 bytes from the nRF51 DK, S130, SDK12 (p0.09 tx) pin to another hardware rx pin.

My Init: uart_init() in main. Baudrate 115200, Flow Control Disabled.

UART: for each byte app_uart_put() to send bytes over uart.

When i take a logic analyzer, i see there are little breaks between the bytes i send.

When i take e.g. HTerm with an usb TTL-232R 3V3 cable there are no breaks between the bytes.

My problem is, if i send this 6 bytes to my external hardware, i should get an response message from hardware to the nRF51 DK. Test with cable i will receive it. But not with the nRF51 DK. Potential is the same! i think this breaks make some trouble. how can i fix it?

Thanks!!

[Ole Bauck]

You can shorten the 21 microseconds a lot. The SDK driver actually starts and stops the transmission for every byte, which is not efficient at all. If you look at the Reference Manual part 29.4 this is not necessary. You can write your own driver to send the bytes.

Actually what I said in the last comment is not the correct time to measure. The time between ENDTX interrupt and TXD being set is about 24us which reflects the total time the nRF51 is doing the processing.