Power Measurements with Astra Machina

Later revisions of Astra Machina contain the two power monitor ICs which can be used to measure the current and voltage of the system. Values can be read using the Linux Kernel’s Hardware Monitoring Interface.

Astra Machina uses the TI INA220 Current and Power Monitor and TI INA3221 Shunt and Bus Voltage Monitor ICs.

Documentation for the hwmon kernel drivers can be found here: ina220 and ina3221.

Performing Measurements

Here is an example of reading Current (mA) channels on SL1640:

cat /sys/class/hwmon/hwmon0/curr1_input （ina322）
856

cat /sys/class/hwmon/hwmon0/curr2_input （ina322）
32

cat /sys/class/hwmon/hwmon0/curr3_input （ina322）
60

cat /sys/class/hwmon/hwmon1/curr1_input （ina2xx）
7

cat /sys/class/hwmon/hwmon2/curr1_input （ina2xx）
67

cat /sys/class/hwmon/hwmon3/curr1_input（ina2xx）
63

Here is an example of reading Bus voltage (mV) channels on SL1640:

cat /sys/class/hwmon/hwmon0/in1_input （ina322）
800

cat /sys/class/hwmon/hwmon0/in2_input （ina322）
840

cat /sys/class/hwmon/hwmon0/in3_input （ina322）
1104

cat /sys/class/hwmon/hwmon1/in1_input （ina2xx）
624

cat /sys/class/hwmon/hwmon2/in1_input （ina2xx）
3384

cat /sys/class/hwmon/hwmon3/in1_input （ina2xx）
1860

Here is an example of reading Power (uW) channels on SL1640:

cat /sys/class/hwmon/hwmon1/power1_input
0

cat /sys/class/hwmon/hwmon2/power1_input
220000

class/hwmon/hwmon3/power1_input
140000

In this example we can calculate total power:

856 * 800 = 684800 uW

32 * 840 = 26880 uW

60 * 1104 = 66240 uW

Total Power = 1137920uW = 1138mW

Supported Boards

Initial versions of Astra Machina did not contain the power monitor ICs. The following table shows the Core Modules and I/O boards which can be used for power measurement.

SoC	Core Module	I/O Board
SL1620	Rev D or later	Rev D or later
SL1640	Rev B or later	Rev D or later
SL1680	Rev C or later	Rev D or later