TMF8829 (Time-of-flight) Arduino Uno driver

This is a simple universal driver to show the capabilities of the time-of-flight devices TMF8829.

Requirements

• an Arduino Uno R3 board
• an ams TMF8829 Arduino Shield Board
• a USB B cable
• the Arduino IDE to compile and download the Arduino Uno example application

Files

The Arduino project in the folder: tmf8829 is a very simple single character command line interpreter listening/printing on UART. The application supports a binary input mode to support configuration commands.

It contains the following files:

• tmf8829.ino - the Arduino specific wrapper for the application
• tmf8829_app.h and tmf8829_app.cpp - the tmf8829 command line application
• tmf8829.h and tmf8829.c - the tmf8829 driver
• tmf8829_shim.h and tmf8829_shim.cpp - a shim to abstract the Arduino specific I2C, UART and GPIO functions
• tmf8829_image.h and tmf8829_image.c - the tmf8829 firmware that is downloaded by the driver as a c-struct

Porting to another MCU

To port the driver and application to another platform you need to adapt the following files:

• tmf8829.ino - the Arduino specific wrapper for the application, replace this with the requirements for your selected platform
• tmf8829_shim.h and tmf8829_shim.cpp - a shim to abstract the Arduino specific I2C, UART and GPIO functions

Demonstrator python scripts

There are also some python scripts:

• talk_to_arduino.py and talk_to_arduino_measure_all_settings.py that shows how to talk to the device in an automated manner. It will also dump all result records into the csv file: tmf8829_arduino_uno_file.csv.

To be able to run the python scripts you need first to program the Arduino Uno example application. The python scripts do not do this.

If you do not have serial installed for python, the pip installation with the requirement file could be used: pip install -r ./requirements.txt

Demonstrator with Evm GUI and/or logger (zmq client)

First the zmq server must be started. The zmq server does the communication with the Arduino driver.

The EVM GUI could be used to do the visualisation. For the focal plane modes 32x32 and 48x32 it is necessary to use a high measurement period. Otherwise the driver cannot read out all frames from the tmf8829 device and frames are lost. The visualisation is then not possible. Visualisation of histograms is only possible for FP-mode 8x8 and FP-mode 16x16 with less iterations and a high measurement period.

The logger could be used to store the data in json format. It is also possible to change the tmf8829 configuration. The description can be found in the Readme of the tmf8829 logger (zmq client).

Note: The default BAUDRATE with 2000000 could show communication errors. In such a case, the zmq server reopens the connection to the Arduino. To get rid of this issue, the BAUDRATE must be reduced (1000000 baud should be sufficient).

Python Sources

There are also python sources for the zeromq server available. See script: tmf8829_zeromq_server_arduino.py

Using the Demonstrator with an Arduino Zero

The Arduino Zero must be programmed with BAUDRATE 1000000. The zmq server tries to find an Arduino Uno. If no device is found, the zmq server tries to find an Arduino Zero.

Using the Demonstrator with another Arduino

The python sources for the zmq server could be downloaded. The function device_connected could be extended for other devices. Add the search for the new device. The USB VID:PID must be known. See the connected com ports, when the server is started.

UART and command line interpreter

The project listens and talks on the UART. Baud rate is 2000000, 8-bit, no parity, 1 stop bit.

The command line interpreter uses single characters followed by ENTER as input commands.

UART commands:

• h ... print help
• d ... disable device
• e ... enable and download firmware
• p ... power down device
• w ... wakeup device
• m ... start measure
• s ... stop measure
• c ... use next configuration
• x ... clock correction on/off toggle
• a ... dump all registers
• u ... get configuration
• z ... histogram dumping on/off
• + ... increase logging output
• - ... decrease logging output
• # ... execute a reset on tmf8829
• b ... Do not use! This character is reserved for binary input commands Note:

Binary Input Commands

To send commands longer than a single character, the binary input mode is used. The zmq server uses the binary input commands for configuration.

A command starts with the character 'b' to switch from single character mode to binary input mode. The binary input command must have the right size to be correctly interpreted and to switch back to single character input mode.

List of commands:

• b'\x31' ... Set arbitrary measurement configuration
• b'\x32' ... Set measurement pre-configuration

Set arbitrary measurement configuration:

• Identifier: b'\x31'
• Payload Size: 190
• Payload has the values of the configuration. A description is found in the datasheet. (Do not modify unused parameters. Therefore, a readout of the configuration should be performed first. Only desired parameters should be changed.)

Set measurement pre-configuration:

• Identifier: b'\x32'
• Payload Size: 1
• Payload has the value of the pre-command. eq: 0x43 for CMD_LOAD_CFG_16X16 (see datasheet register TMF8829_CMD_STAT for available commands)