The TC flag is used in function serial_is_tx_ongoing to check if there is
an ongoing serial transmission. So this Flag must not be cleared at the
end of the transmission, otherwise, serial_is_tx_ongoing will notify that
TX is ongoing.
The impact is that it may prevent deep sleep to be entered.
Also there is no need to clear this flag at the end of the transaction
because it will be cleared automatically by HW when a new transmission
starts.
In serial_tx_active and serial_rx_active functions,
we check the internal state value with
HAL_UART_STATE_BUSY_TX = 0x21U,
HAL_UART_STATE_BUSY_RX = 0x22U,
It seems that value can also be :
HAL_UART_STATE_BUSY_TX_RX = 0x23U,
- serial_init, serial_free and serial_baud function moved from serial_device.c (specific to each STM32 family) to serial_api.c (common STM32 file)
- default baudrate value was hardcoded to 9600
- Value is set now to MBED_CONF_PLATFORM_STDIO_BAUD_RATE for STDIO
- Value is set now to MBED_CONF_PLATFORM_DEFAULT_SERIAL_BAUD_RATE for other use
- UART init will not be stopped before calling serial_baud function
TXE indicates that a byte can be written to UART register for sending,
while TC indicates that last byte was completely sent. So the TXE flag
can be used in case of interrupt based Serial communication, to allow
faster and efficient application buffer emptying.
Also TXE flag will be erased from the interrupt when writing to register.
In case there is nothing to write in the register, the application is
expected to disable the interrupt.
The RXNE flag is getting cleared when reading Data Register so it should
not be cleared here. Especially in case of high data rate, another byte of
data could have received during irq_handler call and clearing the flag
would read and discard this data which would be lost for application.
Depending on families, different HAL macros are defined to check the
state of serial interrupts. In several cases, we can find only 1 macro:
__HAL_UART_GET_IT_SOURCE
Checks whether the specified UART interrupt has occurred or not
But in F0, F3, F7, L0, L4 there are 2 different macros
__HAL_UART_GET_IT
Checks whether the specified UART interrupt has occurred or not
__HAL_UART_GET_IT_SOURCE
Checks whether the specified UART interrupt source is enabled.
In the later case, __HAL_UART_GET_IT_SOURCE was being used so far,
but actually needs to be replaced by __HAL_UART_GET_IT. Using the right
macro, we also check the proper flags accordingly.
Note that this could have side effects on the application as it would
not be aware that data has been missed. This may be later solved by
adding an error management parameter to the Serial API in mbed.
The advantage is that the serial link can work again.
Reworked the serial_format() function for STM32F0x
devices to take the format in the form:
data_bits - parity - stop_bits
E.g. 8 - N - 1
where data_bits exclude the parity bit.
Added a case for 7 bits data as at least the chips
STM32F0x1/STM32F0x2/STM32F0x8 support 7 bits data.
Consolidated serial_format() and uart_init()
functions into a general TARGET_STM serial_api.c
file since the functions are common to all STM targets.
Fixes#4189
jeromecoutant
Laurent Meunier
Yuan Cao
Filip Jagodzinski
bcostm
Francisco J. Manno