zephyr

History

Keith Packard 0b90fd5adf samples, tests, boards: Switch main return type from void to int As both C and C++ standards require applications running under an OS to return 'int', adapt that for Zephyr to align with those standard. This also eliminates errors when building with clang when not using -ffreestanding, and reduces the need for compiler flags to silence warnings for both clang and gcc. Most of these changes were automated using coccinelle with the following script: @@ @@ - void + int main(...) { ... - return; + return 0; ... } Approximately 40 files had to be edited by hand as coccinelle was unable to fix them. Signed-off-by: Keith Packard <keithp@keithp.com>		2023-04-14 07:49:41 +09:00
..
boards
src	samples, tests, boards: Switch main return type from void to int	2023-04-14 07:49:41 +09:00
CMakeLists.txt
prj.conf
README.rst
sample.yaml

README.rst

.. _clock_control_xec:

Microchip XEC (MEC15xx/MEC172x) clock control driver sample application
#######################################################################

Overview
********

This sample demonstrates configuring the 32KHz clock
options via device tree. The application prints out
hardware configuration and exercises some clock control
driver API's.

Building and Running
********************

The sample can be built and executed on boards using west.
No pins configurations, except GPIO014 is used as indicator for entry/exit and
GPIO060 for 48MHZ PLL clock out.
GPIO221 alternate function 1 is 32KHZ_OUT and can be monitored on Assembly 6915 JP7 pin 5.

Internal Silicon 32KHz Oscillator jumper configuration
MEC172x Assembly 6915

   JP1 pin 2 to GND (ground MEC172x XTAL1 pin)
   JP2 No jumper

Dual-ended 32KHz Crystal jumper configuration
MEC172x Assembly 6915

   Jumper on JP1 1-2 connect crystal Y1 pin 1 to MEC172x XTAL1
   Jumper on JP2 2-3 connect crystal Y1 pin 2 to MEC172x XTAL2

MEC172x Assembly 6906 (baseboard)

   Remove jumper on JP121 to prevent U15 32KHz 50% duty waveform
   from coupling to JP2 on Assembly 6915.

External single-ended 32KHz waveform to MEC172x XTAL2 input
MEC172x Assembly 6915

   JP1 pin 2 to GND (ground MEC172x XTAL1 pin)
   Jumper on JP2 1-2 connect external 32KHz signal to XTAL2

MEC172x Assembly 6906 (baseboard)

   Jumper on JP121 pins 3-4 connect U15 32KHz output to
   XTAL2_32KHZ_IN signal routed to XTAL2 MEC172x pin on Assembly 6915

External single-ended 32KHz waveform to MEC172x 32KHZ_IN pin
MEC172x Assembly 6915

   JP1 pin 2 to GND (ground MEC172x XTAL1 pin)
   Remove jumper on JP2

MEC172x Assembly 6906 (baseboard)

   Jumper on JP121 pins 1-2 connect U15 32KHz output to
   32KHZ_IN pin of MEC172x on Assembly 6915

Sample output
=============

.. code-block:: console

   Prints MEC172x VBAT and PCR register pertaining to power on status and
   clock control.