In case a non-gpio EXTI (>= 16) is pending, the isr_exti() used to clear
the flag and try to call a callback, which was out-of-bouds, thus
generating a hard fault.
This fixes it by masking the pending_isr variables with 0xFFFF.
The ram size is exposed as macro value and available for use in code.
For the stm32 it has a value in kilobytes suffixed with 'k'. This is
less than optimal for usage in arithmetic. This commit modifies the
value to bytes so that it can be used in preprocessor magic
This patch implements the basic support the last of the FLEXCOMM modes,
Serial Peripheral Interface, in a simple blocking mode with busy wait,
which is enough to test all the SPI functionality end-to-end.
Tested reading and writing registers on a SPI peripheral, and checked
with the oscilloscope that the frequencies were as expected.
Results from `tests/periph_spi`:
```
> init 0 0 2 -1 0
SPI_DEV(0) initialized: mode: 0, clk: 2, cs_port: -1, cs_pin: 0
> bench
1 - write 1000 times 1 byte: 16002 16009
2 - write 1000 times 2 byte: 18001 18008
3 - write 1000 times 100 byte: 802000 802007
4 - write 1000 times 1 byte to register: 24003 24010
5 - write 1000 times 2 byte to register: 26001 26008
6 - write 1000 times 100 byte to register: 810001 810008
7 - read 1000 times 2 byte: 23003 23009
8 - read 1000 times 100 byte: 807002 807009
9 - read 1000 times 2 byte from register: 32002 32009
10 - read 1000 times 100 byte from register: 816002 816009
11 - transfer 1000 times 2 byte: 23003 23009
12 - transfer 1000 times 100 byte: 807003 807010
13 - transfer 1000 times 2 byte to register: 32003 32009
14 - transfer 1000 times 100 byte to register:816002 816009
15 - acquire/release 1000 times: 7222 7228
-- - SUM: 5059250 5059351
```
The macro was moved from Kconfig to the periph_cpu.h which means that
the macro name needed to be updated to BOARD_HAS_ADC_PA06_CAP instead
of CONFIG_BOARD_HAS_ADC_PA06_CAP.
The ADC in the QN908x cpu offers multiple options for ADC conversion
using up to 8 external pins, one external reference pin and some
internal signals like a 1.2V reference, Vss, Vcc and an internal
temperature monitor.
This patch implements support for sampling ADC values from the ADC lines
defined in the board configuration. Some configurations are really
always present and don't require a board configuration, like the Vcc or
internal temperature monitor but to coexist with other board ADC line
options they are only set as part of the board configuration.
The mv instruction (which is usually implemented as `add rd, x0, r1`) is
changed to `add rd, x0, %input`. This can either be used as a load
immediate or as an move.
The code size grows by two bytes. This because GCC does not compress the
li instruction to the compressed version (even though this is possible).
