Modify UART Class to Make Use of the txBuffer #304
Conversation
per1234
added
type: enhancement
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I pushed another commit that adds the I also noticed that the original commit on this PR also fixes |
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I have tried this change because it makes complete sense and also because I am having issues with the Sparkfun RA6M5 Serial1 port. I have copied the changes as indicated and I had issue :
It then compiled and worked without a problem. FYI The problem was not solved on the RA6M5 with this change..the first character received is somehow 0x0 instead of the expected 0x7E. It is sent by the device as monitored and detected with an external tracer (Saleae). Also the sketch does work unmodified with a UNOR4 Wifi. Different issue |
txc is defined as a member variable of the UART class. I did this because a global would be shared between instances and I didn't want to introduce issues if two UARTs were working at the same time. There is another txc defined in the interrupt callback as a local variable, but it is only used in the context of the handler. That's because the handler doesn't belong to any one instance. |
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Thanks. My error as I missed copying the txc definition from the header file. |
I opened this to replace #303 because it had a bunch of files included from submodules. This should be cleaner. Sorry for the mess.
This pull request makes changes in Serial.h and Serial.cpp so that the UART class will make use of the TxBuffer. This greatly reduces the amount of time that Serial.print will block, especially for long strings. Currently the class makes no use of the 512 bytes it has reserved for a txBuffer.
I've changed the write functions so that they will load characters into the buffer and start a transmission if one is not already going.
Because the HAL takes a pointer to the data, I added a char variable to read into so the buffer can be advanced. I cannot attempt to send a larger portion of the buffer because the HAL expects contiguous memory and it will break in the case where the string to send rolls over the end of the ring buffer. I will submit another PR later to deal with that if I find a good way.
While it is possible to submit an entire string to the HAL at once, the string is submitted by pointer so it creates a possible race if there is some other code that changes the string before it gets fully printed. By utilizing the txBuffer, this problem is also alleviated.
I have tested this code in several configurations and it appears to work just dandy. Please let me know what you think.