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# System prepended metadata

title: CDH data evaluation

---

# CDH data evaluation

1. What do we know? Shortly before the end of the 171 log
    - Last GPS time: 9:13
    - UART Logger stopped on ground
    - GPS height is 477 meter
    - last reset reason was 0x30 which stands for brown out external (power restart), time-wise this is consistent with the RBF
    - CDH has 0.09347A while ADCS has 0.067139. This is explained by the GPS needing 40mA
    - ADCS data looks as expected 
    - GPS data as expected
    - MCU info and power draw as expected 
    - UART Logger wasnt blinking blue, yellow was flickering (after recovery of the balloon on launch day)


2. What we want to do?
    - test with multimeter between cdh and uart logger
    - short dryrun
    - Verify if data from Dry Run (TVAC) shows similar symptoms: big files, but missing some data between
        - see point "TVAC data analysis"

3. TVAC data analysis
    - Looking for data logs with missing time periods in between
    - 125 log from tvac (124 no gps time) and 123 log shows time jump in gps uptime data
        - 123: ends with `{'year': 2021, 'month': 10, 'day': 13, 'hour': 12, 'minute': 27, 'second': 58, 'nanosecondoffset': -302184}`, `{'uptime': 8765006082628, 'reset reason': 48}`
        - 124: no GPS beacons
        - 125: starts with `{'year': 2021, 'month': 10, 'day': 13, 'hour': 13, 'minute': 2, 'second': 44, 'nanosecondoffset': -412742}`, `{'uptime': 10848006126737, 'reset reason': 48}`
    - => Time Jump of ~35 Minutes
    - uptime difference matches data loss
    - CDH board was on, UART logger didnt log
    - all data in log 125 looks as expected (two TOSS not connected)

4. Short dryrun
    - batteries are not equally charged, dryrun will be powered using network generator
    - 7.4 V and 300mA to power the backplane
    - checking slots, all as expected
    - turn on backplane, UART Logger blinks blue which means it receives serial data from CDH 
    - Backplane logger also blinking blue, only power is connected 
    - Click from network generator, resets backplane, possible reason: Globalstar which uses 400mA for sending, waiting 5 minutes for next sending
        - this is not an issue, as the backplane has a more than 1 A fuse
    - possible suspect: config file, uart logger can into command mode where commands can be send to the logger, but this has been disabled
    - clearing cdh sd-card which had cdh data from balloon
    - fault led and uart leds is not on anymore (after roughly 10 mins) which means that there is no UART output from the Backplane, UART Logger on CDH still blinking
    - restarting the whole system and insterting sd-card
    - setting current to 500mA to not run into issues with the globalstar
    - fault led blinking, synchronous with uart led
    - yellow led on cdh uart logger is blinking quickly (blinking is expected)
    - leds on uart logger are controlled by mcu on uart logger
    - waiting for ~6 mins to read out sd-card, expected result: one big continuous file containing all the data
    - clicking is gone, which confirms the thesis of globalstar being responsible for it originally
    - system turned off after roughly 6 minutes 
    - Jonathan evaluates sd-card
    - no data; config.txt as expected, no log recorded
    - insert sd-card and restart with previous values 7.4 V and 500mA
    - after restart: uart logger blinking blue now
    - removed after roughly 1 minute
    - result: many different small logs (check architecture/SE documents/balloon_16_10_2021/UART Outputs)
    - attach oszi to UART2 TX of CDH SSB
    - turn on backplane
    - oszi output looks like UART Output
    - turn off backplane
    - clear all logs on sd card
    - insert sd
    - backplane power on (133mA)
    - looks like UART on oscilloscope, but LEDs on Logger don't fit (yellow is blinking very fast, the blue one is off)
    - every 74ms one byte is sent by the UART logger (HEX 31), stays at 3V3 for 1.39ms, then it goes back to idle
    - slightly pushing the UART logger to the CDH-Board, the UART logger LEDs get darker and sometimes it g