Supercharging the RoboRIO with the BQ32000 from TI
RTC Datasheet:
http://www.ti.com/lit/ds/symlink/bq32000.pdf
Started off with the BQ32000 Module from Evola:
https://evola.fr/en/breakout-boards/813-real-time-clock-module-bq32000.html
It is wired up to the i2c port on the RoboRIO like this:
RTC rRIO
SDA-----SDA
SCL-----SCL
VCC-----3V3
GND-----GND
Next, pulled the kernel driver from the NI git repo here:
https://raw.githubusercontent.com/ni/linux/nilrt_pub/16.0/4.1/drivers/rtc/rtc-bq32k.c
This is a stock driver for Linux mainline from what I can tell.
The stock driver file was modified to remove the need to do anything special to enable the trickle charge feature. This is a hack but it works for this module on this platform.
This is built on the RoboRIO using these directions from NI:
https://forums.ni.com/t5/NI-Linux-Real-Time-Documents/Tutorial-Adding-Kernel-Modules-on-NI-Linux-Real-Time/ta-p/3527186
Note, you may need to add coreutils using opkg.
You will also need to add i2c-tools using opkg.
Summary of steps from the NI Document:
- Pull down these files into a local directory.
- run
source /usr/local/natinst/tools/versioning_utils.sh - run
setup_versioning_env - run
versioning_call make - run
cp rtc-bq32k.ko /lib/modules/`uname -r`/kernel - run
depmod
You should be able to run i2cdetect -y 2 and it will show something like this:
admin@roboRIO-900-FRC:~/rtc-bq32k# i2cdetect -y 2
0 1 2 3 4 5 6 7 8 9 a b c d e f
00: -- -- -- -- -- -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- 68 -- -- -- -- -- -- --
70: -- -- -- -- -- -- -- --
The 68 indicates that the device has been found.
You can now run this to instantiate the device:
echo bq32000 0x68 | tee /sys/class/i2c-adapter/i2c-2/new_device
If you run i2cdetect -y 2 again it will show "UU" instead of 68 indicating that the device is active:
admin@roboRIO-900-FRC:~/rtc-bq32k# i2cdetect -y 2
0 1 2 3 4 5 6 7 8 9 a b c d e f
00: -- -- -- -- -- -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- UU -- -- -- -- -- -- --
70: -- -- -- -- -- -- -- --
Running dmesg will show something like this:
[ 53.975048] bq32k 2-0068: Marshall's in your system messing with your clock!
[ 53.975951] bq32k 2-0068: Enabled trickle RTC battery charge.
[ 53.976784] bq32k 2-0068: rtc core: registered bq32k as rtc0
You can then proceed to set the clock and read from it:
Setting the clock: hwclock.util-linux --systohc --utc
Reading from it: hwclock.util-linux -r -f /dev/rtc