AgOpenGPS - Autosteer PCB - Page 2 - The Combine Forum
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post #11 of 379 (permalink) Old 01-19-2019, 02:55 PM
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Yes, it's the Ethernet module you can stack on the esp32 called huzzah 32.

Others use the feather form factor too:

https://www.kickstarter.com/projects...rm/description

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post #12 of 379 (permalink) Old 01-19-2019, 04:52 PM
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What about a basic nano board without additional a/d. Just the nano, MMA, 5v supply, connections for pwm motor controller or mounts right on the board. Pretty simple.

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post #13 of 379 (permalink) Old 01-22-2019, 07:33 AM
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What about a basic nano board without additional a/d. Just the nano, MMA, 5v supply, connections for pwm motor controller or mounts right on the board. Pretty simple.

That sound great.
But how the connection to the BN0055 ?
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post #14 of 379 (permalink) Old 01-22-2019, 11:09 AM
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That sound great.
But how the connection to the BN0055 ?

Well for now the brick is the solution on its own, but you also only need a nano and 055 in a box on the roof via usb. Not sure best strategy there. I really wish we could do full AHRS in one component, although the MMA and BNO055 together via ethernet is another option. I keep hoping we stumble onto a better alternative then the 055, but so far nope.
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post #15 of 379 (permalink) Old 01-22-2019, 12:00 PM
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Originally Posted by BrianTee View Post
Well for now the brick is the solution on its own, but you also only need a nano and 055 in a box on the roof via usb. Not sure best strategy there. I really wish we could do full AHRS in one component, although the MMA and BNO055 together via ethernet is another option. I keep hoping we stumble onto a better alternative then the 055, but so far nope.
Brian, is the tinkerforge BNO055 the only one that will work or do the BNO's from Adafruit or Sparkfun work the same? Thanks.
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post #16 of 379 (permalink) Old 01-22-2019, 12:46 PM
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Brian, is the tinkerforge BNO055 the only one that will work or do the BNO's from Adafruit or Sparkfun work the same? Thanks.

It would work the same, but there is no code in AOG to receive it. I was always hoping a better solution would come along then the BNO055.
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post #17 of 379 (permalink) Old 01-24-2019, 02:14 PM
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I am building a power supply PCB board with Power In, Power Out (Drive Motor), 8V, 5V, 3.3V and a filtered 5V output to sourced to the 16 bit ADC and source voltage for the WAS.

The attached screenshot of my oscilloscope shows three traces, the Yellow trace is the output of the DC-DC buck converter converting from 13V to 8V, the Blue trace is the output of my Low Drop Out (LDO) 5V regulator, and the Pink trace is the output after my low pass filter (capacitance multiplier) circuit (6.7V).

The vertical scale is set to 50.0mV per division for all three traces. As you can see the output of the DC-DC converter adds a lot of switching noise, almost 100 mV peak to peak. For any analog to digital converter, 10 bit on Arduino or a 16 bit ADC this would be troublesome. Putting the output through a 5V regulator does reduce the noise quite a bit but it is still in the 30 mV range, which may be completely acceptable for most applications. I wanted to reduce the noise even further so I put the output of the DC-DC converted through an "Active" low pass filter. This virtually eliminated all of the switching noise from the DC-DC converter. The input voltage to my filter is 8V while the output was at 6.7V for my given load. Since I will only be driving my 16 ADC and WAS with this source I will still have plenty of head room for my LDO 5V regulator to give a rock solid 5V.

My "active" filter consist of 1 x 56 Ohm resistor, 1 x 47uF cap, and 1 x tip112 darlington pair transistor. Your mileage may vary but this setup should work for my application.
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Last edited by Jays_Truck; 01-24-2019 at 09:30 PM.
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post #18 of 379 (permalink) Old 01-24-2019, 04:26 PM
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Hello,

Very good thing to develop a dedicated pcb for autosteer.
(I've done it on a veroboard with 12 V DCDC - BNO055 - MMA8251 - ADS1115 - PWM drivers around the nano, and this is a nightmare)

Take a chinese 3 V or 5 V DCDC suply, it can handle up to 40 V at the input. Of course add Shotkky diod (or MOSFET) for reverse polarity and fuse.

For the ADS1115, I've made two differential measurements
One for measuring the supply (ADS1115 max analog input is VDD + 0.3)
The other one is differential : one input connected to the steering potentiometer the other one at the middle point of a resistor divider (so offset is near 0)

If you can share a drawing of the schematic, I'm interested.

Best regards
francois
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post #19 of 379 (permalink) Old 01-25-2019, 03:24 AM Thread Starter
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I attached my current state of the PCB. I hope there is enough time on Sunday to build a (mostly mechanical - 4 layer design only two layers for milling) prototype of the pcb. If that's okay and some basic tests works too (e.g. communication between ESP and F9P using external power) I wanted to build a full prototype. And after that I wanted to put the whole project on github.

Using the (currently unused) second Input of the ADS1115 for VCC is a good idea, I'll add that for my pcb too.
Any additional hints are welcome.



greetings
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File Type: pdf mainPCB.pdf (131.5 KB, 79 views)
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Last edited by doppelgrau; 01-25-2019 at 03:38 AM.
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post #20 of 379 (permalink) Old 01-25-2019, 06:33 AM
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Originally Posted by doppelgrau View Post
I attached my current state of the PCB. I hope there is enough time on Sunday to build a (mostly mechanical - 4 layer design only two layers for milling) prototype of the pcb. If that's okay and some basic tests works too (e.g. communication between ESP and F9P using external power) I wanted to build a full prototype. And after that I wanted to put the whole project on github.

Using the (currently unused) second Input of the ADS1115 for VCC is a good idea, I'll add that for my pcb too.
Any additional hints are welcome.



greetings
Looks great, but what about heatsink dimension for the motor drivers? The pcb cooling design (page 27 here https://www.st.com/content/ccc/resou...DM00213876.pdf ) doesn´t look of much compared to the big ribs on the IBT_2. IBT_2 goes to 43 amps, and the VNH7070ASTR goes to 15 amps each.


Last edited by LarsVest; 01-25-2019 at 06:54 AM. Reason: added amps
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