Synopsis

Data Acquisition (DAQ) device based on the ADC in TI Tiva C microcontroller.

This utility provides a means for configuring each of the (four) sequencers the on the (two) ADCs in Tiva C (TM4C123) microcontroller in JSON format and obtaining the data in a set of CSV files (one per sequencer) on the host.

The hardware is not abstracted, by design. There are no "virtual channels" that are magically mapped to physical ADC hardware. Instead, the ADC hardware is presented to the user as it is. In order to make sense of the configuration, it is necessary to read the TM4C123 datasheet that describes the ADC sequencer hardware architecture. However, the means of configuration are at a high level (JSON) for convenience. The data delivery chain from the ADC, to packets on UART, all the way to CSV files on the host is deliberately abstracted.

Example usage outline:

1. Configure the hardware in adc-config.json, for example:

   { "adcs": { "0": { "triggerTimer": { "idx": 1, "half": "A" }, "samplesPerSec": 10, "hwAvgFactor": 16, "seqs": { "0": { "name": "voltages", "priority": 2, "trigger": "timer", "bufSize": 512, "samples": [ { "Vin": "A0" }, { "Vout": "A1" }, ] }, "1": { "name": "diff_voltages", "priority": 1, "trigger": "timer", "bufSize": 128, "samples": [ { "Vdiff": "D0" } ] }, "3": { "name": "errata_tm4c123_rev_6_7_ADC14", "priority": 0, "trigger": "timer", "bufSize": 128, "samples": [ { "errata": "D0" } ] }, "2": { "name": "environment", "priority": 1, "trigger": "processor", "bufSize": 64, "samples": [ { "temp": "TS" } ] } } } } }

2. Configure application (UART ports, baud rate, logging, etc.) in daq.cfg.

3. Build and flash the target application (see section below).

4. Setup data recording on the host. The following assumes a UART->USB hooked up to UART port 1, since port 0 is used for console log output (configurable in daq.cfg):

    $ stty -F /dev/ttyUSB0 raw
    $ cat /dev/ttyUSB0 > example.dat
   

5. Reset the board (by default, data collection starts on reset).

6. Parse the data stream into CSV (third arg is the prefix for output files):

    $ host/daq-to-csv.py tivadaq/daq-config.json example.dat example
   

7. Find your data in <prefix>.<sequence_name>.csv:

    $ head example.voltages.csv
    Vin,Vout
    3.299194,1.465503
    3.299194,1.474365
   
    $ head example.environment.csv
    temp
    15.592651
    15.713501
   

Dependencies

• XDCTools >= 3.30

• SYSBIOS (also part of TI-RTOS v2)

• TivaWare (also part of TI-RTOS v2)

• rtsc-platforms: custom packages that build on top of lower-level libraries (TivaWare and parts of SYSBIOS) to allow convenient usage of the Tiva platform from RTSC components, by providing hardware attribute info, LED and UART Console IO.

• OpenOCD: for flashing the application to the target device.

The build-env.sh script shows environment variables that need to be pointed to the installation paths. The script can be modified and sourced:

$ . build-env.sh

Build and Flash

$ xdc all -PR tivadaq
$ openocd -f openocd/ek-tm4c123gxl.cfg -c 'program tivadaq/daq.xm4fg 0x0'