This is a development branch and a work in progress that is not fully completed or documented. The original Logenv is available on the classic branch or as release v1.0.
logenv is a Linux command-line utility for the aggregating, logging, charting and displaying of timestamped CPU core frequencies, thermal zone temperatures, ambient temperature, CPU core usage, memory usage, sensors data and volts, amps and watts, from a HardKernel SmartPower2 or SmartPower3, as a single-shot or continuos interval based feed. Many sensors are supported and logenv can also generate GNUplot scripts for any collected data set, as well as provide a UDP network stream. Local display of data on small oled and eInk displays is supported for the SSD1306, SH1107 and SSD1681 controllers.
License: GPLv3.
cjson and gpiod are required to compile logenv while gnuplot is only needed if generating charts. Any OS repository version of cjson should work but gpiod version 1.x is needed until 2.x is supported. If gpiod version 1.x is not available in your repository then compile gpiod v1.64 from source.
cjson https://github.com/DaveGamble/cJSON
gpiod v1.x https://libgpiod.readthedocs.io/en/stable/
wget https://mirrors.edge.kernel.org/pub/software/libs/libgpiod/libgpiod-1.6.4.tar.xz
tar -xvf ./libgpiod-1.6.4.tar.xz
cd ./libgpiod-1.6.4/
./configure --enable-tools
make
sudo make install
If the installed library path is not in the ldconfig cache then add the library path(default /usr/local/lib) on a new line at the end of /etc/ld.so.conf or create an entry in the directory /etc/ld.so.conf.d.
$ sudo vi /etc/ld.so.conf
add /usr/local/lib or installed path
$ sudo ldconfig
or
$ echo "/usr/local/lib" | sudo tee /etc/ld.so.conf.d/custom.conf
$ sudo ldconfig
git clone https://github.com/hominoids/logenv.git
cd logenv
make
usage: logenv [options]
Options:
-l, --log <file> Log to <file>
-i, --milliseconds <number> Polling Interval <number> in milliseconds
-d, --date Date and Time stamp
-f, --frequency CPU core frequency
-t, --temperature Thermal zone temperature
-u, --usage CPU core usage, aggregate and core 0 to core n-1
-m, --memory Physical memory usage (total - available, see man free)
-p, --smartpower3-ch1 <tty> Volt, Amp, Watt (HK SmartPower3 USBC port), default /dev/ttyUSB0
--smartpower3-ch2 <tty>
--smartpower2 <tty> Volt, Amp, Watt (HK SmartPower2 microUSB port), default /dev/ttyUSB0
-a <sensor> Ambient Temperature sensor to use (e.g. --bme280) for Thermal chart
--mcp9808 <device> High Accuracy Temperature Sensor I2C 0x18 default /dev/i2c-0
--sht4x <device> Temperature and Humidity I2C 0x44 default /dev/i2c-0
--shtc3 <device> Temperature and Humidity I2C 0x70 default /dev/i2c-0
--aht20 <device> Temperature and Humidity I2C 0x70 default /dev/i2c-0
--htu31d <device> Temperature and Humidity I2C 0x40 default /dev/i2c-0
--bme280 <device>@addr Temperature, Humidity, Pressure Sensor I2C 0x76 or 0x77 default /dev/i2c-0
--bme680 <device> Temperature, Humidity, Pressure & VOC Sensor I2C 0x76 or 0x77 default /dev/i2c-0
--bmp180 <device> Barometric Pressure, Altitude & Temperature Sensor default /dev/i2c-0
--bmp388 <device> Barometric Pressure, Altitude & Temperature Sensor I2C 0x76 or 0x77 default /dev/i2c-0
--bmp390 <device> Barometric Pressure, Altitude & Temperature Sensor I2C 0x76 or 0x77 default /dev/i2c-0
--sgp30 <device> VOC and eCO2 Sensor I2C 0x58 default /dev/i2c-0
--scd30 <device> CO2 Temperature and Humidity Sensor I2C 0x61 default /dev/i2c-0
--scd41 <device> CO2 Temperature and Humidity Sensor I2C 0x62 default /dev/i2c-0
-r, --raw Raw output, no formatting of freq. or temp. e.g. 35000 instead of 35
-q, --quiet No output to stdout
-v, --verbose Readable dashboard output
-n, --udp <host>:<port> UDP output to <host>:<port>
-g, --gnuplot <file> Gnuplot script generation
--title <string> Chart title <string>
--xmtics <number> Chart x-axis major second tics <number>
-o, Display output on eInk/Oled/LCD using configuration logenv.json
--version Version
-h, --help Help screen
This example is a typical data collection and charting workflow:
Every 2 seconds collect the CPU frequency, thermal zone temperatures, CPU usage, SmartPower3 Volt, Amp and Watts, and mcp9808 as ambient temperature.
./logenv -l ocl-m2_g610-a76_1.csv -i 2000 -f -t --mcp9808 -u -p
Generate the GNUplot script
./logenv -g ocl-m2_g610-a76_1.gpl --title "OpenCL-Benchmark Odroid-M2 GPU-CPU" --xmtics 60 -i -f -t -a --mcp9808 -u -p
Generate the chart
gnuplot -c ocl-m2_g610-a76_1.gpl ocl-m2_g610-a76_1.png ocl-m2_g610-a76_1.csv
Settings for the Hard Kernel SmartPower3 and SmartPower2 are baud rate 115200,8N1 with no HW or SW control.
Many types of sensors are directly supported using built in drivers and require no other setup. At this time only I2C access is available for those that also have a SPI interface. The I2C device and or the address can follow any sensor argument while using the command line interface, otherwise the default values are used. The I2C address follows standard C language notation for decimal, hex or octal e.g. 119, 0x77, 0167
logenv --bme680
--bme680 /dev/i2c-0
--bme680 /dev/i2c-0@119.
--bme680 /dev/i2c-0@0x77.
--bme680 /dev/i2c-0@0167.
aht20 - Temperature & Humidity I2C ADD 0x38
htu31 - Temperature & Humidity I2C ADD 0x40
sht40,sht41,sht43,sht45 - Temperature & Humidity I2C ADD 0x44
shtC3 - Temperature & Humidity I2C ADD 0x70
mcp9808 - High Accuracy Temperature Sensor I2C ADD 0x18
bme280 - Pressure, Altitude, Temperature & Relative Humidity, ADD 0x76 or 0x77
bme680 - Pressure, Altitude, Temperature, Relative Humidity & VOC ADD 0x76 or 0x77
bmp180 - Barometric Pressure, Altitude and Temperature
bmp388 - Barometric Pressure, Altimeter and Temperature I2C ADD 0x76 or 0x77
bmp390 - Barometric Pressure, Altimeter and Temperature I2C ADD 0x76 or 0x77
scd30 - NDIR True CO2 (400ppm – 10,000ppm), Temperature and Humidity Sensor ADD 0x61
scd40,scd41,scd43 - True CO2, Temperature and Humidity Sensor ADD 0x62
sgp30 - VOC and eCO2 I2C ADD 0x58
The kernel industrial IO(iio) sensors can be read by using the iio command instead of the sensor command. The iio sensor name, as presented in the device tree and in /sys/bus/iio/devices/iio:device0/name, is used to identify the correct sensor entry since the iio device number is not persistent across system boots. The JSON device entry is used to identify the file system file name to read for the sensor datum e.g. /sys/bus/iio/devices/iio:device0/in_illuminance_input
{
"cmd": "iio",
"name": "tsl2591",
"device": "in_illuminance_input",
"address": 0,
"dtype": "",
"xloc": 10,
"yloc": 40,
"color": 0,
"font": "MONOSPACE_16",
"label": "illum: ",
"unit": ""
},
Single or stacked charts are created based on the type and number of datum that are contained in the data set. Core Frequency, Thermal Zone Temperatures, Ambient Temperature, CPU core usage, memory usage, SmartPower and sensor data can all be charted. When a GNUPlot Script file is generated, part of it's contents is based on the number of CPU cores and the number and name of thermal Zones. For this reason the GNUPlot script needs to be generated on the machine the data was collected from if any of those datum are included. The GNUPlot Scripts or .gpl files can be reused and don't need to be regenerated if the type of data being collected and the machine are the same.
The UDP client -n option is followed by the server host and port host:port. The host entry can be either an IP address or host name. Make sure the port is open if using a firewall. From the command-line on the server host system, netcat can be used to read the UDP feed.
netcat -l -u -p <port>
The timing accuracy for both the logging and display functions are dependant on the number and type of data being collected. Some sensors can inject significant latency due to the time it takes for readings. This is especially true for those sensors that require heaters, e.g. MOX sensors, or other pre-read initialization process. If the logging, UDP or display functions are simultaneously being used, they share the same data read for each interval which reduces the number of sensor and data reads, and thereby reducing latency.
The display configuration file logenv.json is a JSON formatted file that describes a display, its pages and content for each page. The current working directory is searched first (./logenv.json) and then /etc/logenv/logenv.json. Multiple displays are supported with each capable of multiple pages containing time, date, system information or sensor data. Each display must contain at least one page - page 0. Subsequent page entries are identified by increasing the page number and setting the seconds for that page to be displayed.
{
"displays": [
{
"name": "ssd1306",
"device": "/dev/i2c-1",
"address": 61,
"xsize": 128,
"ysize": 64,
"rotation": 0,
"page": 0,
"seconds": 60,
"contrast": 125,
"segment_column_address": 1,
"scan_direction_start": 1,
"left_right_remap": 0,
"pin_config_alt": 1,
"vcom_deselect": 2,
"content": [
{
"cmd": "time",
"name": "",
"device": "",
"address": 0,
"dtype": "",
"xloc": 15,
"yloc": 5,
"color": 0,
"font": "DEFAULT_24",
"label": "",
"unit": ""
},
{
"cmd": "date",
"name": "",
"device": "",
"address": 0,
"dtype": "",
"xloc": 35,
"yloc": 30,
"color": 0,
"font": "DEFAULT_12",
"label": "",
"unit": ""
},
{
"cmd": "iio",
"name": "tsl2591",
"device": "in_illuminance_input",
"address": 0,
"dtype": "",
"xloc": 5,
"yloc": 50,
"color": 0,
"font": "DEFAULT_12",
"label": "illum:",
"unit": ""
},
{
"cmd": "sensor",
"name": "mcp9808",
"device": "/dev/i2c-0",
"address": 24,
"dtype": "F",
"xloc": 70,
"yloc": 50,
"color": 0,
"font": "MONOSPACE_12",
"label": "",
"unit": "c"
}
]
}
]
}
Most entries in the json file are self explanatory with the possible exception of the initialization variables segment_column_address, scan_direction_start, left_right_remap, pin_config_alt and vcom_deselect. These entries only apply to SSD1306 and SH1107 displays and are set to a 0 or 1 value to enable or disable the configuration command with the exception of vcom_deselect.
The first two, segment_column_address and scan_direction_start, control the direction and starting column address. If the oled is displaying upside down, change the segment_column_address and scan_direction_start values to the opposite. If they are 0 change them to 1 and retest.
If there are horizontal trace lines on the screen the vcom_deselect may need adjusting:
0 = deselect level 0.65
2 = deselect level 0.77
3 = deselect level 0.83
Any of the page content command can be used for any display type and can be called more then once.
- date
- disk
- frequency
- governor
- hostname
- iio
- ip
- kernel
- memory
- sensor
- swap
- sysload
- text
- thermal
- time
- uptime
- usage
date
COMMAND: date
DESCRIPTION: displays date at xloc, yloc using font.
DTYPE: dd
mm
yy
mm/dd/yyyy
dd/mm/yyyy
yyyy/mm/dd
short Fri 01-May-26
long Friday 01 May 2026
day Friday
month May
year 2026
EXAMPLE:
{
"cmd": "date",
"name": "",
"device": "",
"address": 0,
"dtype": "long",
"xloc": 10,
"yloc": 40,
"color": 0,
"font": "DEFAULT_16",
"label": "",
"unit": ""
},
disk
COMMAND: disk
DESCRIPTION: displays mounted disk info at xloc, yloc using font.
DEVICE: path
DTYPE: free
used
percent
EXAMPLE:
{
"cmd": "disk",
"name": "",
"device": "/",
"address": 0,
"dtype": "free",
"xloc": 10,
"yloc": 40,
"color": 0,
"font": "MONOSPACE_16",
"label": "/ ",
"unit": "G free"
},
frequency
COMMAND: frequency
DESCRIPTION: displays core name and frequencies at xloc, yloc using font.
DEVICE: empty for all cores or core number
DTYPE: D = datum
N = name
DN = datum name
ND = name datum
EXAMPLE:
{
"cmd": "frequency",
"name": "",
"device": "",
"address": 0,
"dtype": "D",
"xloc": 10,
"yloc": 40,
"color": 0,
"font": "MONOSPACE_16",
"label": "",
"unit": ""
},
governor
COMMAND: governor
DESCRIPTION: displays governor from device at xloc, yloc using font.
DEVICE: path to sysfs entry
EXAMPLE:
{
"cmd": "governor",
"name": "",
"device": "/sys/devices/system/cpu/cpufreq/policy0/scaling_governor",
"address": 0,
"dtype": "",
"xloc": 10,
"yloc": 40,
"color": 0,
"font": "MONOSPACE_16",
"label": "CPU: ",
"unit": ""
},
hostname
COMMAND: hostname
DESCRIPTION: displays hostname at xloc, yloc using font.
EXAMPLE:
{
"cmd": "hostname",
"name": "",
"device": "",
"address": 0,
"dtype": "",
"xloc": 10,
"yloc": 40,
"color": 0,
"font": "MONOSPACE_16",
"label": "",
"unit": ""
},
iio
COMMAND: iio
DESCRIPTION: displays kernel iio sensor at xloc, yloc using font.
NAME: name of sensor as defined in /sys/bus/iio/devices/iio:device0/name
DEVICE: sensor datum entry to display in /sys/bus/iio/devices/iio:device0/
DTYPE: divide / or multiply * sensor datum by a single scalar as a post process.
EXAMPLE:
{
"cmd": "iio",
"name": "tsl2591",
"device": "in_illuminance_input",
"address": 0,
"dtype": "/10",
"xloc": 10,
"yloc": 40,
"color": 0,
"font": "MONOSPACE_16",
"label": "illum: ",
"unit": ""
},
ip
COMMAND: ip
DESCRIPTION: displays named network interface ip at xloc, yloc using font.
NAME: interface name
DTYPE: D = datum
N = name
DN = datum name
ND = name datum
EXAMPLE:
{
"cmd": "ip",
"name": "eth0",
"device": "0",
"address": 0,
"dtype": "ND",
"xloc": 10,
"yloc": 40,
"color": 0,
"font": "MONOSPACE_16",
"label": "",
"unit": ""
},
kernel
COMMAND: kernel
DESCRIPTION: displays kernel version at xloc, yloc using font.
EXAMPLE:
{
"cmd": "kernel",
"name": "",
"device": "",
"address": 0,
"dtype": "",
"xloc": 10,
"yloc": 40,
"color": 0,
"font": "DEFAULT_12",
"label": "kernel ",
"unit": ""
},
memory
COMMAND: memory
DESCRIPTION: displays memory usage at xloc, yloc using font.
EXAMPLE:
{
"cmd": "memory",
"name": "",
"device": "",
"address": 0,
"dtype": "",
"xloc": 10,
"yloc": 40,
"color": 0,
"font": "MONOSPACE_16",
"label": "",
"unit": ""
},
sensor
COMMAND: sensor
DESCRIPTION: displays sensor datum at xloc, yloc using font.
NAME: aht20,htu31,sht40,sht41,sht43,sht45,shtc3,mcp9808
bme280,bme680,bmp180,bmp388,bmp390,
scd30,sdc40,scd41,scd43,sgp30
DTYPE: C = Celsius
F = Fahrenheit
H = Humidity
P = Pressure
G = Gas
V = VOC
EXAMPLE:
{
"cmd": "sensor",
"name": "bme680",
"device": "/dev/i2c-1",
"address": 119,
"dtype": "C",
"xloc": 5,
"yloc": 50,
"color": 0,
"font": "DEFAULT_12",
"label": "",
"unit": "c"
},
The sensor address is 7-bits I2C address in decimal e.g. 119 = 0x77
swap
COMMAND: swap
DESCRIPTION: displays swap info at xloc, yloc using font.
DEVICE: path
DTYPE: total
free
used
percent
EXAMPLE:
{
"cmd": "swap",
"name": "",
"device": "",
"address": 0,
"dtype": "percent",
"xloc": 10,
"yloc": 40,
"color": 0,
"font": "MONOSPACE_16",
"label": "swap ",
"unit": "%"
},
sysload
COMMAND: sysload
DESCRIPTION: displays sysload info at xloc, yloc using font.
DTYPE: short [%d] [%d] [%d]
long 1min(%d) 5min(%d) 15min(%d)
EXAMPLE:
{
"cmd": "sysload",
"name": "",
"device": "",
"address": 0,
"dtype": "short",
"xloc": 10,
"yloc": 40,
"color": 0,
"font": "MONOSPACE_16",
"label": "",
"unit": ""
},
text
COMMAND: text
DESCRIPTION: displays string at xloc, yloc using font.
DEVICE: string of up to 255 characters
EXAMPLE:
{
"cmd": "text",
"name": "",
"device": "This is a Test.",
"address": 0,
"dtype": "",
"xloc": 10,
"yloc": 40,
"color": 0,
"font": "MONOSPACE_16",
"label": "",
"unit": ""
},
thermal
COMMAND: thermal
DESCRIPTION: displays thermal temps at xloc, yloc using font.
DEVICE: empty for all zones or zone number
DTYPE: D = datum
N = name
DN = datum name
ND = name datum
EXAMPLE:
{
"cmd": "thermal",
"name": "",
"device": "0",
"address": 0,
"dtype": "ND",
"xloc": 10,
"yloc": 40,
"color": 0,
"font": "MONOSPACE_16",
"label": "",
"unit": "c"
},
time
COMMAND: time
DESCRIPTION: displays time at xloc, yloc using font.
DTYPE: empty 4:00 PM
12 04:00
24 16:00
EXAMPLE:
{
"cmd": "time",
"name": "",
"device": "",
"address": 0,
"dtype": "24",
"xloc": 10,
"yloc": 40,
"color": 0,
"font": "MONOSPACE_36",
"label": "",
"unit": ""
},
uptime
COMMAND: uptime
DESCRIPTION: displays uptime at xloc, yloc using font.
DTYPE: short %d days HH:MM
long %ddays, %dhours, %dminutes
EXAMPLE:
{
"cmd": "uptime",
"name": "",
"device": "",
"address": 0,
"dtype": "short",
"xloc": 10,
"yloc": 40,
"color": 0,
"font": "MONOSPACE_16",
"label": "",
"unit": ""
},
usage
COMMAND: usage
DESCRIPTION: displays CPU and core usage at xloc, yloc using font.
DEVICE: empty for all cores or core number, 0 is total usage
DTYPE: D = datum
N = name
DN = datum name
ND = name datum
EXAMPLE:
{
"cmd": "usage",
"name": "",
"device": "",
"address": 0,
"dtype": "ND",
"xloc": 10,
"yloc": 40,
"color": 0,
"font": "MONOSPACE_16",
"label": "",
"unit": ""
},
DEFAULT_12, DEFAULT_16, DEFAULT_24
MONOSPACE_12, MONOSPACE_16, MONOSPACE_20, MONOSPACE_24, MONOSPACE_28,
MONOSPACE_36, MONOSPACE_48
Basic display capability has not been fully implemented so only limited display tests have been performed. More testing will occur as development proceeds.
ssd1681 AdaFruit 4196 1.54" Monochrome 200x200 eInk / ePaper Display
ssd1306 Odroid-HC4 Monochrome 128x64 OLED graphic display
ssd1306 AdaFruit 938 Monochrome 1.3" 128x64 OLED graphic display
sh1107 AdaFruit 5297 Monochrome 1.12" 128x128 OLED graphic display
st7789 AdaFruit 3787 Color 1.54" 240x240 Wide Angle TFT LCD display
logenv has been tested with both a HardKernel SmartPower2 and SmartPower3, including MCP9808 and BME280 sensors. Several architectures have been test including Armv7, Armv8, Armv9 and different generations of INTEL and AMD processor up to 32 cores. The current limitation is 256 cores. It has also been used on several Linux distributions including Ubuntu, Debian, Manjaro and Arch. It should run on just about anything that runs Linux.