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Problem with USART TX irq on LPC546XX

Question asked by SST Informatique on Apr 1, 2019
Latest reply on Apr 8, 2019 by jeremyzhou



When using a usart, and enabling tx irq, I get  a permanent call to the irq routine (permanent = once we return from the irq routine, we get back to it without any time to execute something else).


To reproduce : use lpcxpresso54608_usart_example from sdk, and replace in "usart_interrupt.c" the line 

USART_EnableInterrupts(DEMO_USART, kUSART_RxLevelInterruptEnable | kUSART_RxErrorInterruptEnable);


USART_EnableInterrupts(DEMO_USART, kUSART_TxLevelInterruptEnable );


The problem has been reproduced with this program on lpc54608 (om13098) and lpc54606 (custom board).


The original problem has also been detected on a mbed generated project on our custom board.

We got the same behaviour for all the usart we are using (0,2, 4 and 6).