Another week! Man, do they come around fast. I’ve made some small progress, both with the oscilloscope tester and ebike controller.
The oscilloscope tester is slowly moving forwards - I’ve soldered a few up boards, but before I launch them on their website I’d like a good batch, just on the off chance a few people might buy them!
Therefore, I’ve ordered enough components to make 50 or so. One issue I was having was my liquid flux ‘baking’ on. I tried to remove it with IPA, and a few other things, but nothing would budge it:
Then I came across “Flux-Off” by chemtronics. And it worked wonders:
After some IPA (to remove the dull shine you can see above) it’s perfectly clean. The flux was #835 by mgchemicals, it’s a great flux but damn is it hard to move.
ebike_controller_update1.pdf (279.2 KB)
I’ve recently been working on the IO of the STM32 - usually these pins are already assigned in the projects I work on, so it’s been fun trying to see what pins have what alternate functions, and swapping them such that I can get all the functionality I want.
One thing I’d like is to measure the battery voltage and currents (and, at some point, write them to the SD card) and so I’ve been looing into that this past week. For work, I’ve been designing a ultra precise current measurement circuit. Overall accuracy isn’t an issue, but precision was paramount. So, I’m quite familiar with the types of parameters for op amps that affect current measurements. It didn’t take me long to find a cheap, but suitable current amplifier op-amp. I’ve added a filter, a decade below the motor switching frequency.
For the voltage measurement, that’s quite simply a potential divider, with another filter. I added a zenner since this is a direct connection from battery to MCU.
The next steps are to add the SD card electronics, LCD electronics, the interface to the throttle and add the connectors to the outside world, until next week!
Max