Battery Voltage Not being reported.
fatdollar opened this issue · comments
The battery voltage being reported by my system is 0V using both Mission Planner and QGroundControl. I have tried different settings within both of those control stations but I am always getting 0V. Is there a setting on the board that needs to change?
Have you come across this issue?
I con't really want to fly this until I can safely monitor my battery levels. In addition it doesn't pass pre-flight checks anyways unless I override the battery check.
Any ideas?
Hi,
Some info about ArduPilot voltage & current sensing:
An0 is for voltage and An1 is for current. You'll need a voltage divider (multiturn potentiometer) to get the voltage down to a MAXIMUM of 1.8 V on the two ADC pins (0 and 1).
The ADCs are accessible via the linux file system.
To read ADC 0: cat /sys/bus/iio/devices/iio:device0/in_voltage0_raw
To read ADC 0: cat /sys/bus/iio/devices/iio:device0/in_voltage1_raw
It's a 12-bit converter, so you read from 0 to 4096.
Here's how the battery monitor is defined: https://github.com/ArduPilot/ardupilot/blob/master/libraries/AP_BattMonitor/AP_BattMonitor_Analog.h#L66
Rather than use a voltage divider, the best option would be to make a little op amp circuit - offset and gain to have maximum span (1.8 V span compared to 300-400 mV span with a divider).
Hope this helps.
-- Anthony
Hello,
I configured the battery voltage indicator to work without the need for any additional hardware like a voltage divider. Indeed, if you look at the BeagleBone Blue Rev. A2 schematics below, AIN6 already measures the LiPo battery voltage through a voltage divider, while AIN5 measures the DC Jack voltage (also through a voltage divider):
Please note that I'm using ArduCopter V.3.6.10.
Here are the steps to configure using QGroundControl (daily build from 19 sept. 2019), but similar things might also be done with APMPlanner2 or Mission Planner:
Connect using QGroundControl.
Set BATT_MONITOR to "Analog Voltage Only" and save:
Close QGroundControl.
Restart the arducopter (for example arducopter-heli):
sudo systemctl restart arducopter-heli.service
Relaunch QGroundControl.
Set BATT_CURR_PIN to Disabled and save:
Set BATT_VOLT_PIN to 6 as "Manual Entry" (6 for AIN6) and save:
After this, you should see an approximate indication of the battery voltage.
Set BATT_VOLT_MULT to 11.037:
Note: 11.037 is a value specific to my hardware and is provided here as an indication. This value should be calibrated according to your hardware-specific voltage divider resistors ratio, by measuring the battery voltage with a multi-meter.
You might also set the "BATT_CRT_VOLT" to around 6.2V, "BATT_LOW_VOLT" to around 6.4V and "BATT_CAPACITY" according to you battery capacity. Finally, set the "Minimum arming voltage" under the Power Setup Menu:
It should also be noted that the "Power Setup Menu" provides a very convenient calculator for the voltage calibration.
Hope this helps.
-- Vlad
Hi Anthony,
Surely you should add-it in your excellent guide! You made an amazing job by collecting all this valuable information! Thanks to your work, I was able to compile the flight controller in an evening. I still need to get the necessary hardware, but I am very impatient to install it on my own helicopter (an old Raptor 30 v2).
Here are three topics from my own experience that you might also add to the guide, if you think necessary:
- After changing the services files (as indicated in you guide), I has some strange behaviors. Therefore, I recommend always make a:
sudo systemctl daemon-reload
every time a service file changed, to make sure the systemd manager configuration is reload.
- The battery indicator LEDs (BATT_LED_1, BATT_LED_2, BATT_LED_3, BATT_LED_4) are very useful because they visually report the battery charging status and also the voltage level:
The Robot Control Library (https://github.com/StrawsonDesign/librobotcontrol) includes a such nice service, named "rc_battery_monitor" at https://github.com/StrawsonDesign/librobotcontrol/tree/master/services/rc_battery_monitor
Below are the instructions on how to install the rc_battery_monitor service (derived from http://strawsondesign.com/docs/librobotcontrol/installation.html):
sudo apt update && sudo apt upgrade librobotcontrol
To the question "_Which program to run on boot?", answer "none".
After the installation, the service is automatically enabled and active:
The BATT_LED_1, BATT_LED_2, BATT_LED_3 and BATT_LED_4 leds should now be active.
Run this command to check the service is running:
systemctl status rc_battery_monitor.service
The robotcontrol service should be stopped and disabled (this service fails to start because module 'pru_rproc' and 'pruss_soc_bus' are missing - probably because of a wrong kernel version):
sudo systemctl stop robotcontrol.service
sudo systemctl disable robotcontrol.service
You might also run the rc_battery_monitor interactively. For this:
sudo systemctl stop rc_battery_monitor.service
sudo /usr/bin/rc_battery_monitor
2S Pack Jack #Cells Cell
8.15V 12.18V 2 4.08V
After that, don't forget to start the service back by issuing a:
sudo systemctl start rc_battery_monitor.service
Note: In https://github.com/StrawsonDesign/librobotcontrol/blob/master/library/src/io/adc.c, the V_DIV_RATIO is set to 11.0. For a more precise calibration this value might be configurable by the user.
- Finally, here are pair of utility scripts to watch the voltage on the AINs:
cat adc1.sh
#!/bin/bash
while true; do cat /sys/bus/iio/devices/iio:device0/in_voltage* | paste - - - - - - - - ; sleep 1; done
and
cat adc2.sh
#!/bin/bash
watch -n 1 -td 'echo "AIN0\tAIN1\tAIN2\tAIN3\tAIN4\tAIN5\tAIN6\tAIN7"; cat /sys/bus/iio/devices/iio:device0/in_voltage* | paste - - - - - - - - '
These scripts might be useful during the test of an airspeed meter sensor or other device providing an analog signal.
Best regards,
--Vlad
Hi Antony,
I wanted to play with the Robot Control Library mentioned in my previous post. This library provides a lot of nice examples and diagnosis tools located in /usr/bin/rc_* like:
rc_altitude rc_calibrate_gyro rc_test_adc rc_test_encoders rc_test_motors
rc_balance rc_calibrate_mag rc_test_algebra rc_test_encoders_eqep rc_test_mpu
rc_battery_monitor rc_check_battery rc_test_bmp rc_test_encoders_pru rc_test_polynomial
rc_benchmark_algebra rc_cpu rc_test_buttons rc_test_escs rc_test_pthread
rc_bind_dsm rc_dsm_passthrough rc_test_complementary_filters rc_test_filters rc_test_servos
rc_blink rc_kill rc_test_dmp rc_test_kalman rc_test_time
rc_calibrate_accel rc_model rc_test_dmp_tap rc_test_leds rc_test_vector
rc_calibrate_dsm rc_spi_loopback rc_test_drivers rc_test_matrix rc_uart_loopback
rc_calibrate_escs rc_startup_routine rc_test_dsm rc_test_mavlink rc_version
Note: according to https://docs.px4.io/master/en/flight_controller/beaglebone_blue.html, the PX4 Flight Controller running on BeagleBone Blue, uses librobotcontrol robotics package (build with librobotcontrol with PX4 extensions and with realtime kernel as an option).
The documentation of librobotcontrol is here: http://strawsondesign.com/docs/librobotcontrol/examples.html
Robot Control Library requires a new way of communicating with the on-board PRU's, known as RPROC, instead of the UIO (Linux Userspace I/O interface) used by ArduPilot. In the past, UIO needed a 'bone' version of the kernel, while the 'rproc' a 'TI' kernel version (mutually exclusive). Now, the latest TI kernels are compatible with both versions, however the "uboot_overlay_pru" option of "/boot/uEnv.txt" must be set accordingly.
For this:
sudo /opt/scripts/tools/update_kernel.sh --lts-4_19 --ti-rt-channel
Tweak /boot/uEnv.txt like :
###pru_rproc (4.19.x-ti kernel)
uboot_overlay_pru=/lib/firmware/AM335X-PRU-RPROC-4-19-TI-00A0.dtbo
###pru_uio (4.4.x-ti, 4.14.x-ti, 4.19.x-ti & mainline/bone kernel)
#uboot_overlay_pru=/lib/firmware/AM335X-PRU-UIO-00A0.dtbo
Then:
sudo reboot
After reboot:
rc_test_drivers
Kernel: 4.19.73-ti-rt-r27
BeagleBoard.org Debian Image 2019-09-08
Debian: 9.11
PASSED: gpio 0
PASSED: gpio 1
PASSED: gpio 2
PASSED: gpio 3
PASSED: pwm0
PASSED: pwm1
PASSED: pwm2
PASSED: eqep0
PASSED: eqep1
PASSED: eqep2
PASSED: pru-rproc
PASSED: uart1
PASSED: uart2
PASSED: uart4
PASSED: uart5
PASSED: i2c1
PASSED: i2c2
PASSED: spi
PASSED: LED
PASSED: ADC iio
Currently running on a:
MODEL_BB_BLUE
Robot Control library Version:
1.0.4
Check that all passed.
Once you played with examples from "/usr/bin/rc_*", tweak back the "/boot/uEnv.txt" for ArduPilot :
###pru_rproc (4.19.x-ti kernel)
#uboot_overlay_pru=/lib/firmware/AM335X-PRU-RPROC-4-19-TI-00A0.dtbo
###pru_uio (4.4.x-ti, 4.14.x-ti, 4.19.x-ti & mainline/bone kernel)
uboot_overlay_pru=/lib/firmware/AM335X-PRU-UIO-00A0.dtbo
sudo reboot
WARNINGS:
- I don't tested the --lts-4_19 --ti-rt-channel kernel with ArduPilot, despite it seems to work (I'm still waiting for some hardware). Maybe you can do some fly tests and update the guide?
- If you have problems with the ti-rt-channel kernel, then roll back with:
sudo /opt/scripts/tools/update_kernel.sh --lts-4_19 --bone-rt-channel
sudo reboot
References:
- http://strawsondesign.com/docs/librobotcontrol/installation.html
- https://gist.github.com/jonlidgard/1d9e0e92b4f219f3f40edfed260b851e
Hope this helps.
-- Vlad
No problem!🙂 I suspect that the TI RT kernel would be less efficient than the bone RT.
htop with bone RT kernel:
htop with TI RT kernel:
