The minimal version of the data logger is very simple to use. There is no display and keyboard therefore everything has to be done using the red LED on the microcontroller, the BCD DIL switch and an attached TTL cable.

Common Procedure

  1. Select the desired mode using the mode selector.
    Mode Selector
  2. Turn the controller on using the power switch.
    Data Logger Power Switch

If a TTL cable is attached, the device is powered from this cable. In this case enable the “charge switch” to power the whole device from this cable, and turn the power on. Because you can not turn off the power of  the controller, use the reset switch on the microcontroller board to select a new mode.

The Modes

There are several modes available:

Number Description
0 Log data in 10 second intervals.
1 Log data in 30 second intervals.
2 Log data in 1 minute intervals.
3 Log data in 10 minute intervals.
4 Log data in 1 hour intervals.
5 Log data in 4 hour intervals.
6 Log data in 8 hour intervals.
7 Log data in 24 hour intervals.
8 Read all records and send them to TTL.
9 Format the storage. This will erase all logged values.

The Log Mode

If the data logger starts in one of the various log modes, it will add new records to the storage in the selected interval. It will try to save as much power as possible while this process.

You can attach a TTL cable and open the serial console at 57600 baud before selecting this mode to get some details about the logging process before it starts. Here an example of the output:

Lucky Resistor's Data Logger Version 1
Logging selected. Interval = 10s
Maximum records: 170
Current records: 41
Available records: 129
Recording time: 21 minutes 30 seconds.
Current time: 2015-08-23 14:52:54
Recording end time: 2015-08-23 15:14:24

In the first line after the header you see the selected mode and the selected logging interval. The other lines are explained in the following table.

Name Description
Maximum records The maximum number of records which can be stored in the memory of the data logger.
Current records The current number of records stored in the memory.
Available records How many records can be recorded.
Recording time The recording duration which is possible with the current available records.
Current time The current time which is the start time for the recording and will be the time of the first record.
Recording end time The time when the recoding has to stop because the memory is full. If the battery gets empty, this can be much earlier.

The Read Mode

The read mode is to transfer all stored records to the computer using a TTL cable. Attach a TTL cable and open the console at 57600 baud. Make sure the charge switch and power switch are enabled and the blue LED on the PowerBoost 500 is on.

If you missed the start of the data, just press reset to get the whole list again. See the following example how the output can look like:

Lucky Resistor's Data Logger Version 1
Read selected. Sending 170 records.
2015-08-23 11:58:30,26,44
2015-08-23 11:58:50,26,44
2015-08-23 11:59:20,26,44
2015-08-23 11:59:50,26,44
2015-08-23 15:14:00,27,43
2015-08-23 15:14:10,27,43
Finished successfully. Enter sleep mode.

Now you can copy all the values into a CSV file and open it in your favourite spreadsheet program. There you can do various analyses and create nice diagrams.

Data Logger Spreadsheet

The Format Mode

You can use the format mode to prepare the memory for the first time you use the data logger or to erase all previously recorded records.

After selecting this mode, the red LED on the microcontroller board starts a countdown from one up to ten flashes. After this countdown, the memory is erased.


Errors are reported using the red LED on the microcontroller. The LED flashes a number of times with a longer pause between. Just count the number of flashes which will give you the error number.

The LED “double” flashes at the start. This is caused by the boot loader which indicates it is waiting for a connection. For this reason all real error signals starting from the number three.

Number Description
3 This error is reported if the real time clock is not running. It means you probably never initialised the clock properly or after some years the coin battery is empty.
5 This error is reported if the memory is full and no more records can be recorded.

Continue reading: Parts

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