Set the betweenTransferDelay to the SCK low-time, to avoid long pauses
between bytes (transfers) while preventing the last SCK cycle in a byte
from being a runt pulse.
Compared to an earlier revision of this change, which just set the delays
all to zero, this doesn't break using an AirLift, which was sensitive
to the runt pulses (the simple loopback-wire test didn't detect the problem)
without this, the baud rate could be wrong; in my testing, it was
low by a factor of 2 when requesating baudrate=1_000_000 (1MHz).
When passing the baudrate in to LPSPI_MasterInit, the setting is made
automatically, but LPSPI_MAster_SetBaudRate just returns it via the
out-parameter tcrPrescaleValue.
There are DNP resistors on the MIMXRT1010-EVK board (see SCH-45852)
that lead to these pins on the arduino-style header not being connected
through. In theory someone could populate them, but as it the presence
of these names in the pins module caused problems when they didn't work
as expected.
Closes#3012
This commit simplifies and cleans up the bare-arm port, and adds just
enough system and library code to make it execute on an STM32F405 MCU.
The mpconfigport.h configuration is simplified to just specify those
configuration values that are different from the defaults. And the
addition of -fdata-sections and -ffunction-sections means the final
firmware is smaller than it previously was, by about 4200 bytes.
A README is also added.
Signed-off-by: Damien George <damien@micropython.org>
This switches stage2 to C and uses Jinja to change the C code based
on flash settings from https://github.com/adafruit/nvm.toml. It
produces the fastest settings for the given set of external flashes.
Flash size is no longer hard coded so switching flashes with similar
capabilities but different sizes should *just work*.
This PR also places "ITCM" code in RAM to save the XIP cache for
code execution. Further optimization is possible. A blink code.py
still requires a number of flash fetches every blink.
Fixes#4041
The I2C.c for RP2040 included a special case for writes <=2 bytes to match the MicroPython implementation,
however RP2040 does support 1 and 2 byte reads, with only 0 bytes being the exception.
Signed-off-by: Philip Howard <phil@pimoroni.com>
