Note: Not planning on selling or distributing what I’m showing off. As a one man project I cannot live with the responsibility of others using my stuff as I’m way under qualified to create these kind of things.
"Blogg entry #1 - 2020-08-06"
I’ve been here before showing a bit of my custom control system. I’m not a big fan of pixhawk and the software and I love engineering on stuff like this. No education just a bunch of trials and failures hopefully soon ending in success. I’ll update this first post when I get news for this system.
I’ve been running this successfully for about 15-20 dives using a raspberry pi and a lot of adafruit breakout boards glued / screwed to a 3d printed hat. This shows me that it is possible.
My newest adventure is creating a custom PCB for the Raspberry PI. I’ve created 4 revision. Luckily none of them have been a success. Why luckily you might ask. Oh, well… I’ve just yesterday after ordering Rev 4 that the gripper needs 3v3 PWM. Not 5V pwm as I designed. So that was another 30 dollar down the drain as the order was too late to stop.
Working 5-6 hours on designing the PCB this is now what I have:
Features I’ve added so far on rev 5:
- 16 pins for PWM signals.
- 3v3 PWM signals on all pwm pins. (do’h)
- Voltage and current sensor
- 3 Leak Sensor headers (credits to BlueRobotics for the schematic, I kinda stole the idea… Sorry! )
- 3 external I2C headers with 3v3 up to 200mA
- Pressure, humidity and temperature sensor (BME280)
- Accelerometer, magnometer and gyro for those roll, tilt and heading readings!
- Direct 2-4 cell connection on the PCB just solder on a connector
- 2 switching voltage regulators, 3A 5V to the raspberry pi and 2A 5V to the PWM header rows.
A bit of history for my self:
Rev 1: Lots of wrong wire connections. Swapped SLC and SDA, did not hook up the ADC e.t.c.
Rev 2: Added a unsupported Gyro which did not work with raspberry pi.
Rev 3: Some wrong wire connections. Also the chip i wanted to use is way to expensive. Found a cheaper one with both gyro and accelerometer built in + magnometer. So i decided to again go back to the pcb drawing board to order REV 4…
Rev 4: On its way, but I here found out that using 5V PWM would kill the gripper… So i redesigned to use 3v3.
Rev 5: On its way, ordered yesterday. Hopefully this is the working one. I’ll at least make it working and test dive with it then redesign any flaws.