EYE ON NPI - ams OSRAM TMF8806 Single-Zone direct Time of Flight sensor

Adafruit Industries

This week's EYE ON NPI is having Too Much Fun - it's the ams OSRAM TMF8806 Single-Zone direct Time of Flight sensor (https://www.digikey.com/en/product-highlight/a/ams/tmf8806-single-zone-tof) the latest in ams' series of ToF sensors. This sensor may seem like "YAToF" but there's a few things that caught our eye. One is the excellent pricing, about $2 in quantity. Another is the simplicity of function: unlike many ToF sensors, there isn't a massive firmware stack required to load on each boot. Instead, the default firmware is in ROM for a lightweight interface. We've stocked ToF sensors (https://www.adafruit.com/search?q=tof) for quite a while - mostly the ST VL series. These sensors have developed quite a bit over the years, starting with the 100mm-range VL6180 (https://www.adafruit.com/product/3316) and continuing onto multi-grid devices that we've covered on previous EYE ON NPI's (https://www.youtube.com/watch?v=3PocFz427NE). The way these work is by blasting laser pulses out of a VCSEL (https://en.wikipedia.org/wiki/Vertical-cavity_surface-emitting_laser) which then bounces off of the target and the 'time of flight' is measured in the pF range to give accuracy and range. Easy to describe, but non-trivial to implement...the light doesn't bounce off perfectly, and a lot of individualy measurements need to be taken and then averaged - this is called the histogram. The histogram data is filtered in software to toss outliers and double-bounces, to get the 'true' calibrated distance. And it has to do this dozens of times a second. The complexity of the algorithm is what gives each product its accuracy, precision, repeatability and range - so its no surprise that its running on an in-package microcontroller. However, as the sensors have gotten more advanced, the firmware process has also gotten complex: for many ToF sensors you have to 'load' the firmware algorithm on boot (https://github.com/STMicroelectronics/stm32-vl53l5cx/blob/main/modules/vl53l5cx_buffers.h#L33) and even if you don't, its a non-trivial port to other platform. That's what caught our eye for the ams OSRAM TMF8806 (https://www.digikey.com/short/f9v8w20d), the description specifies "No FW download is required to operate this device, saving host MCU memory space, reducing startup time, and saving overall system power by enabling customers to quickly start the device and make measurements in a few milliseconds". The interface is trivial, they even provide the I2C commands required to boot, load firmware, and perform a reading, its about a dozen commands. For hardware, it's also a nice and simple integration - with a small OLGA package, I2C communication, and 1.8V or 3.3V logic level. One thing to watch for, the sensor comes with 3 'modes' - short, medium and long range. Minimum range for all of these is 10mm, the max is 200, 2500 or 5000mm. And,while the sensor can do 5000mm, it requires pretty specific calibration and lighting. The default range is 2500 and we recommend sticking to that if you can because then you get the benefit of built-in configuration and calibration for speed/simplicity. To get started fast, ams OSRAM supplies multiple drivers for Arduino or other C microcontrollers (https://github.com/ams-OSRAM/tmf8806_driver_arduino), generic Python (https://github.com/ams-OSRAM/tmf8806_driver_python) and Linux kernel (https://github.com/ams-OSRAM/tmf8806_driver_linux). You can also grab an eval board in 'shield' format that has a microcontroller for plug-and play usage (https://www.digikey.com/en/products/detail/ams-osram-usa-inc/TMF8806-EVM-EB-SHIELD/24768739) Add low power, super fast ToF sensing to your next design with the ams OSRAM TMF8806 Single-Zone direct Time of Flight sensor (https://www.digikey.com/short/f9v8w20d), in stock for immediate shipment from DigiKey! Order today and it will ship to you at pico-second speed, so that you can be integrating it by tomorrow morning.