This week I focused on a combination of getting firmware rolling, wrapping up PCB part sourcing, schematics, and layouts, and working with the team on integrating the full communication pipeline from BLE tag to hub to web app.
Last week, I focused way too much on setting up the ble tag firmware development environment and finishing the PCB’s at the cost of working more on the design report – I wrote the abstract did a little bit of editing, but little more than that. Luckily, several of the system diagrams and notes on hardware tradeoffs I made before came in handy in the report, but I definitely should have actively worked on it more.
What that time went into was firmware development, hardware development, and parts sourcing. Firstly, I jumped through several painful hoops getting the Keil development environment, Dialog SDK, and SmartSnippets Toolbox all working on my Mac (after a lot of time spent on stuff not working properly, I bit the bullet, bought Parallel, and set it up on a Windows VM). The result is that I can actively develop firmware for the USB dev kit as well as our future custom tags. With the LED blinking, I have the hello world I wanted to get. The tags can actively be run from a debug build and I confirmed that permanently flashing them also works.
On the PCB front, things are not as far along as I’d hoped, but still steadily moving along. The parts are all selected for the weight and rfid sensor portions, and I have completed the design of breakouts for the main chips. This just leaves the primary tag pcb left, with just a little work left to be done on getting the SPI Flash memory chip and SWD JTag done.
Finally, I used the PCB mill at my job’s office to get the prototype breakout boards cut out:
It’s great to actually have these things physically in my hands!
I have been actively chugging through datasheets for the DA14531 ble/mcu, the spi flash, the accelerometer, the rfid chip, and the hx711 adc/amplifier. Next week, I’ll aim to have the ble usb dev kit reading values from the HX711 (connected to the load cell). In other words, next week will see the weight sensing up and running and (hopefully) displaying live data in the web app.