Datalogger

ATMega328-based custom data logger hardware & firmware files. Currently, this project reads location data from a GPS module and writes it to a .csv file on an SD card. It is designed to work with a BN-220 GPS module.

Details of design, testing, and issues can be found here https://notes.benjemmett.com/archives/375

Warning!

This project is in a rough draft state and currently includes significant hardware design issues.

• Incorrect exposed pad connection in 5v linear regulator
• GPS connector pad order does not match the cable provided with the BN-220 GPS module
• Missing FTDI DTR pin connection for programming with the Arduino bootloader
• Incorrect SD Card detect wiring causes light to always be on

Log File Format

The log file consists of the BN-220 data written directly to a csv file. It can operate in two modes:

1. Record only GGA messages
2. Record all messages

The Log File name format consists of a the date and a record number followed by the ".csv" extension. The format is as follows, DDMMYYXX.csv where:

• DD is the day of the month
• MM is month
• YY is the year
• XX is a record number incremented on each startup in the range [0-99] For example, if the next record number is 42 and the current date is April 20, 2023 and the version number is 00 then the filename would be 20042342.csv

Indicator Lights

The board includes 5 status LEDs numbered 0 to 4, where LED 0 is closest to the MCU. LED 0 indicates a critical error has occured.

Startup sequence is as follows:

1. Indicate DIP switch position.
2. If DIP 1 is enabled, LED_3 blinks 3 times
3. If DIP 2 is enabled, LED_4 blinks 3 times
4. Each LED blinks one time briefly in order from LED_0 to LED_4
5. Slow LED_1 toggling indicates an SD card failure. SD Card initialization is retried every 500ms until successful.
6. Three fast LED_1 blinks indicates successful SD card initialization.
7. LED_2 blinks indicate that GPS is being read and checked for synchronization before continuing.
8. LED_1 & LED_2 simultaneous blinks indicate that GPS data is being read until a valid date and time stamp is found.

During data collection:

• LED_3 is illuminated while reading GPS data
• LED_4 is illuminated while writing data to the SD card
• LED_0 is illuminated if there is an SD card write error