Remove pretty catastrophic loop in the USART serial transmit handler #25
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causing CPU to stay in interrupt handler more or less the entire time untill the character was transmitted. Thus blocking out other interrupts, such as receive on other ports, and also wasting CPU resources.
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Thanks! I haven't had time to review the other PRs just yet, but this bug sure is ugly! So everything now acts normally when this line is removed? |
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All fine now. I discovered it when investigating a problem with lost characters on Serial receive, and found it got worse the more you were transmitting on other channels. Found it by doing a code review of UART.cpp and friends. The bug is easily verified by incrementing a (volatile) counter in the while loop, where one will discover the CPU spends a lot of time in that loop. |
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@egilkv should this PR be updated with what came out of the discussion in megaavr PR#42? |
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For now it is fine. I am also working on a proper fix/cleanup, which I think is ready but I want to do more testing before I signal final go-ahead. Will keep you posted. |
The new Arduino megaavr serial driver has a serious issue in the transmit interrupt
handler causing tjhe CPU to stay in interrupt handler more or less the entire time
until the character is fully transmitted. Thus blocking out other interrupts,
such as receive on other ports, and also wasting CPU resources.