I decided to Change the 12 x PWM Hat to use High Side Current Sensors. Below is the schematics of the new sensors. This means I measure current out on each PWM signal. Using high side sensors actually simplified the routing so it was a straight forward change. The reason I started with low side…
This 12 x PWM Hat have 12 x high side current sensors. The PWM driver have a separate PSU, DRV8313 is rated 60V and INA194 is rated -16 to 80V so they are not that easy to break giving the Hat a very decent protection level. A separate TVS and capacitor bank on motor PSU…
This Hat was actually a challenge to route, but I managed it at the 4th attempt. I am quite happy with the result as well. Raspberry PI Hat Format STM32F405RG MCU, 32bit ARM M4, 168Mhz, 1Mb Flash, 196Kb SRAM. 42Mbps backbone network. ca 30Mbps With Raspberry PI. CAN Network USB Separate PSU for PWM 12…
The 2 blue signals crossing the bigger, red Power lane is asking for trouble. The blue lanes are 0-3V ADC signals, while the power lane is feeding PWM MOSFET’s. What will happen is that PWM noise from current spikes will jump over to ADC signals and create a false current signature. But, I believe it…
I must admit that sourcing for STM32F405RG is an issue. I have bought batches from China and I am rejecting a lot of MCU’s. The worst is actually the time to solder them on before I can test, so I seriously need the tester shown in my last article. This is worst as I like…
Finally – I just discovered test boards with sockets for STM32 LQFP64 and LQFP100. They are a bit pricy – ca 65.- USD yet, but it is a start. These are on the list of things I planned to make because I could not buy them.
I currently plan using INA194 that have a 50x gain. As our max voltage in is 3.3V this means the max voltage over the shunt need to be 3.3/50= 66mV. Given a max current of 2.5A that gives a Shunt resistor R = V/A = 0.066/2.5 = 0,0264 R or 25mOhm. Now – 2.5A over…
Left side of the 3-Phase/Stepper/PWM Hat done. This is the hardest bit, but it went much easier this time because the previous attempts gave some hints and lessons learned. I am far from finished, but it is not hopeless. My main concern is the ground-plane getting to fragmented and unable to support the currents –…
I am returning to this board to make a new attempt because it is a very attractive board to make + I just received another bunch of DR8313 chips and Connectors that I need to use for something. What stalled me on the last attempt was several issues: 12 x current sensors are a bit…
Message Header This is the new message format that I will use on SPI, RS485 and Ethernet. For CAN I am not sure yet. I might want to take more advantage of the strong capabilities in CAN, but lets see. The format above allows me to communicate device to device in a network, but at…