Same as in the main code.
Use Timer1 as baudrate generator.
Timer1 can be programmed to have the same accuracy and deviation as
Timer2, up to 115200 at F_SYS = 125 Mhz. See comment
setup_serial_timer1() comment for valid baudrates and settings.
Timer1 is used in 8-bit auto-reload mode.
Only differance is that the serial is transmit only and poll-based so no
interrupts are used to transmit data.
In commit 884bc18, `Fast Read 0x0b` was exchanged for `Read 0x03` command.
This was done because I did not see the difference between the commands
and the extra dummycycles looks like wasted time. But I overlooked that
many flash devices, the `Read 0x03` command can't run at the maximum
SPI-clock speed, but only half or less of the maximum SPI-clock speed.
This can cause in-transit data corruption while reading the device.
So change it back to `Fast Read 0x0b` command, so the SPI device is used
within the device specification.
TI-interrupt flag is used in the code, this is only
fine when SERIAL-interrupt is not enabled/used but
when is it used, it generates an interrupt which is
not handled, so it keeps generating interrupts and
trashing the performance and caused starvation on
lower priority interrupts like TIMER 2.
Use an extra flag to signal to the code that the
TX-buffer is empty.
Use Timer1 as baudrate generator.
Timer1 can be programmed to have the same accuracy and deviation as
Timer2, up to 115200 at F_SYS = 125 Mhz. See comment
setup_serial_timer1() comment for valid baudrates and settings.
Timer1 is used in 8-bit auto-reload mode.
Timer2 16-bit auto-reload can now be used for other tasks like SYS_TICK.
Downside of Timer0 is, we have to manually reload
the timer value. Timer2 can do that automaticly.
This saves a lot of time in the interrupt-handler
of the Timer.
Currently Timer2 is used for baudrate-generation
but in a separete commit this is moved to Timer1.
A `%` modulo operator was used instead of a
`&` and-operator, to split a 16 bit value into two
8 bit values.
This causes that the SYSTICKs were 0.1% too fast.
Replace the manual split with a sfr16 type, so the
compiler does the split for us.
René van Dorst
logicog
logicog