S32K118 UART over FlexIO IDLE time between bytes

[joseponc]

Hello.

I'm having some communication issues while trying to use UART over FlexIO. Everything seems to work just fine while communicating at 1Mbps. However, my application needs to send multiple messages to multiple devices and sadly, a broadcast does not comply with my application needs. This leads to bus overload and eventually, messages start colliding and I start having communication issues. 

My current workaround for this issue involves having my communications scheduler trigger less frequently. This way there is more space for my messages to be sent. I also thought I'd to increase my communication baud rate as well and check how it behaves. From what I see in the communication bus, it's not quite doing so: I can see that, whenever there is a data transmission, it is transmitted at the new, higher baud rate. However, there is a noticeable gap between each byte transmitted which takes even more time than the transmitted byte, hence, making the communication frame take the same amount of time to be transmitted at 1Mbps and at 2Mbps. 

Evidence: 

Communication frame at 1Mbps:

Same Communication frame at 2Mbps:

Do you have any suggestion for this behavior? I'm currently using the FlexIO driver provided in the S32DS SDK and using the blocking function. 

Thanks in advance.

Regards,

Jose.

[Robin_Shen]

Hi Jose,

Please refer to the flexio_uart_s32k118 example in S32DS v3.4+SDK RTM4.0.3.
FLEXIO_UART_DRV_SendDataBlocking should be able to send several bytes. If you configure txSize=6, it can send these 6 bytes together.

Best Regards,
Robin
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[joseponc]

Hello Robin.

Thanks a lot for the reply and sorry for the delay on my side.

My parameters sent to the function are the exact same in both screenshots. In both cases my txsize is 6. The only thing I'm changing is the baud rate.

Regards,

Jose.

[Robin_Shen]

Hi Jose,

Communication frame at 1Mbps:

Same Communication frame at 2Mbps:

[joseponc]

Hello Robin.

That's what I'm doing and that's the behavior I want. However, that's not what I'm getting.

See screenshot of my configuration:

And I selected my FlexIO source to be the FIRC.

Regards,

Jose.

[Robin_Shen]

Which version of SDK are you using? Have you tested the (SDK RTM 4.0.3) project I sent you privately? I also choose the FlexIO source as FIRC in that project. From the screenshot of your configuration, only the FlexIO pins are different from mine.