We added a check to make sure the pins are in a high state before
initing the bus. This leads to a friendly error message when someone
forgets to add the pull up resistors to their circuit.
Before this change, `microcontroller.cpu.uid` returned values
where the top 4 bits of each byte were zero, because of
an incorrect bitmask used in this function.
CPython doesn't allow SEEK_CUR with non-zero offset for files in text mode,
and uPy inherited this behaviour for both text and binary files. It makes
sense to provide full support for SEEK_CUR of binary-mode files in uPy, and
to do this in a minimal way means also allowing to use SEEK_CUR with
non-zero offsets on text-mode files. That seems to be a fair compromise.
.. the price of this appears to be about 112 bytes of flash and 12
bytes of RAM, according to the stats printed during the build.
It also uses up 4 directory entries (out of 128), but does not reduce
the number of blocks usable for storing file contents.
These are the same items noted in the Adafruit README for Trinket M0
as preventing MacOS indexing.
Closes: #689
Building with gcc 5.4.1 (Debian Stretch) with the unsupported
-Wno-error=lto-type-mismatch flag removed, the following diagnostic
occurs:
../../py/builtin.h:121:19: error: type of 'circuitpython_help_text' does not match original declaration [-Werror]
extern const char MICROPY_PY_BUILTINS_HELP_TEXT[];
^
../../shared-bindings/help.c:38:13: note: previously declared here
const char *circuitpython_help_text =
^
lto1: all warnings being treated as errors
lto-wrapper: fatal error: /usr/bin/arm-none-eabi-gcc returned 1 exit status
The following error occurs when building with gcc 5.4.1 (debian stretch):
common-hal/busio/UART.c:104:83: error: 'sercom_index' may be used uninitialized in this function [-Werror=maybe-uninitialized]
sercom_insts[rx->sercom[j].index]->USART.CTRLA.bit.ENABLE == 0) ||
It may be related to the addition of rx-only UARTs; gcc is unable
to infer the intended relationship between have_tx and sercom_index
being set (I am still not entirely confident of it myself)
Having the `active_read = false` in the background function left
a chance that a new_write occurs before active_read is set to false.
In that case, we'll read the appropriate data rather than write it
and never clear the active write.
Hopefully fixes#655.
