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Discussion Starter #1
Hi,

after Brian mentioned it and there had been already some PCBs in the autosteer-thread, I wanted to start an own thread, since I currently plan to design a PCB myself.

My goal is to reduce the "cable clutter". Only the steering angle sensor, the GPS-Anenna, the motor and of course power should be cables (and the additional RS232 GPS output if used).

Current idea:

  • As microcontroller an ESP32 WROOM dev board (connected using pin header)
  • GPS with the ardusimple F9P (connected via pin header, secured with PCB-distance holder)
  • Power regulator on the "main PCB" for 3,3V and 5V
  • serial out for GPS-data (MAX3232)
  • Outputs for autodrive (TPL7407LA - 12V 0,5A)
  • Inputs for workswitch, autosteer button, counter (future use)
  • wheel angle sensor input (ADS1115) - with a jumper for 0-5V or a linear potentiometer (and a good reference voltage)
  • roll with a MMA 8452
  • no heading, since that would be useless inside the cabin with all the steel and electric nearby?!
  • motor driver with one or two H-bridges (e.g. VNH7070ASTR)
  • if some IOs are needed for the autodrive-output or status LED a MCP23016T
Software: "steal" and modify from weder/coffeestrack

  • Ntrip-client (internet from tablet or router)
  • GPS out over Wifi or Bluetooth
  • "normal" autosteer, IMU (roll) and the autodrive relais-inputs over wifi.
Some open questions:


  • Should the board be designed for 12V (9-15V) input, or for 24V input voltage (so dcdc-converter for 24V for the motor and the board)?
    In that case a third "internal voltage" would be needed for 12V (for the autodrive outputs), but that could be the reference voltage for linear potentiometer the same time, so no big difference except a bigger regulator.
  • How much input protection is needed (I'd say some ESD for AutoSteer and work switch, since there is human interaction everyday)
  • Should a bno055 be placed on the board, even it's inside the cab with all the steel an electric currents?
 

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Hi,

after Brian mentioned it and there had been already some PCBs in the autosteer-thread, I wanted to start an own thread, since I currently plan to design a PCB myself.

My goal is to reduce the "cable clutter". Only the steering angle sensor, the GPS-Anenna, the motor and of course power should be cables (and the additional RS232 GPS output if used).

Current idea:

  • As microcontroller an ESP32 WROOM dev board (connected using pin header)
  • GPS with the ardusimple F9P (connected via pin header, secured with PCB-distance holder)
  • Power regulator on the "main PCB" for 3,3V and 5V
  • serial out for GPS-data (MAX3232)
  • Outputs for autodrive (TPL7407LA - 12V 0,5A)
  • Inputs for workswitch, autosteer button, counter (future use)
  • wheel angle sensor input (ADS1115) - with a jumper for 0-5V or a linear potentiometer (and a good reference voltage)
  • roll with a MMA 8452
  • no heading, since that would be useless inside the cabin with all the steel and electric nearby?!
  • motor driver with one or two H-bridges (e.g. VNH7070ASTR)
  • if some IOs are needed for the autodrive-output or status LED a MCP23016T
Software: "steal" and modify from weder/coffeestrack

  • Ntrip-client (internet from tablet or router)
  • GPS out over Wifi or Bluetooth
  • "normal" autosteer, IMU (roll) and the autodrive relais-inputs over wifi.
Some open questions:


  • Should the board be designed for 12V (9-15V) input, or for 24V input voltage (so dcdc-converter for 24V for the motor and the board)?
    In that case a third "internal voltage" would be needed for 12V (for the autodrive outputs), but that could be the reference voltage for linear potentiometer the same time, so no big difference except a bigger regulator.
  • How much input protection is needed (I'd say some ESD for AutoSteer and work switch, since there is human interaction everyday)
  • Should a bno055 be placed on the board, even it's inside the cab with all the steel an electric currents?

12 volt, would be my suggestion. Those convertors can run pretty hot so good to exclude from the case.
BNO, definitely not.
Make sure pinouts work for ethernet, I'm sure this is already done. All need to do is plug in the ethernet card and hook up the cable.

If everything is in the box, then minor such as the steer switch.
I would also suggest, make people conform to the board, don't get bogged down with making it fit everyone's need. Software can be changed and uploaded, a board not so much.

Maybe a bit of a prototype spot on the board, extra pads to connect etc, but I would hope there is only 1 main version.
 

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Sounds good so far, the VNH7070AS is able to split into half bridges, so also hydraulic valves could be managed.
Have seen at some newer Tractors a third Valve which completely disconnect the pressure from the 2 PWM valves, so a second VNH7070AS would be a good idea.

(Also some additional valves for "reaction" or Open Center could be handled without additional hardware.

Maybe optionaly the powering of the ADS could be disconnected in order to connect it with the tractors 5V to avoid tractor faults if the preinstalled sensor is also used by the tractor itself.
 

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Discussion Starter #5
Make sure pinouts work for ethernet, I'm sure this is already done. All need to do is plug in the ethernet card and hook up the cable.
An LAN8720 for the integrated MAC in the ESP32, or did you have some other Chip in mind?

Maybe a bit of a prototype spot on the board, extra pads to connect etc, but I would hope there is only 1 main version.
Yeah, I guess a few IO-Pins on a pinheader for "future use" won't be a problem and a good idea.

Sounds good so far, the VNH7070AS is able to split into half bridges, so also hydraulic valves could be managed.
Have seen at some newer Tractors a third Valve which completely disconnect the pressure from the 2 PWM valves, so a second VNH7070AS would be a good idea.
ok, so I plan with two VNH7070AS, if only a motor is used the outut could be bridged to reduce the (thermal) load.

Maybe optionaly the powering of the ADS could be disconnected in order to connect it with the tractors 5V to avoid tractor faults if the preinstalled sensor is also used by the tractor itself.
Is that still a problem, if you use the differential measurement feature?
 

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An LAN8720 for the integrated MAC in the ESP32, or did you have some other Chip in mind?

I was so focused on the Nano, The question doesn't make sense - but maybe it does.

The benefit of the nano and the encj60 is you just plop the ethernet down first instead and then put the nano on top. Ethernet that way takes up no board space.



Is there something similar for the ESP32?


700 × 700
 

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I’m really a fan of the ESP32.
For the design might it be useful to use a ready platform. I would suggest Adafruit feather. There you can switch to another chip, if the ESP32 won’t be there in some years. Additionally add-ons like Ethernet are easy by stacking in a feather wing. The cons are: its more expensive (5,- extra) and not all GPIOS are out.

For the general installation I would do a

roof unit:
ESP32 + F9P + BNO + MMA + 5V Power supply
WiFi for the NTRIP, UDP IMU signal, Bluetooth or Ethernet for GPS (NMEA)
We can use a waterproof housing (15x15x6cm) and put the antenna on top. So the only cable would be power. Additionally we can add a Battery and a charge controller so it’s a mobile unit for finding landmarks.

Separate Steercontroller:
ESP32 + ADS + IBT + 12->24 stepup
Wifi for UDP steerdata

Separate Section control via WiFi UDP

So if using WiFi and Bluetooth, no cable except of power to the Computer.

The software for the ESP32 and the code for AOG is already done/in testing…..

All units are simple in wiring by taking I2C.

Just my 2ct

Greeting Matthias
 

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Discussion Starter #8
My idea was to avoid a roof-unit to avoid the problems (and costs) to get everything waterproof (only the antenna is exposed to the weather) and avoid communication problems if the roof is made of metal.

Of course, that "limit" the mobile usage of the GPS receiver.
 

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My idea was to avoid a roof-unit to avoid the problems (and costs) to get everything waterproof (only the antenna is exposed to the weather) and avoid communication problems if the roof is made of metal.

Of course, that "limit" the mobile usage of the GPS receiver.
I have to go outside, because there is no space inside. For the steercontroller I hardly found a place for the ITB. Vineyard tractor.
 

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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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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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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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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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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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Discussion Starter #19 (Edited)
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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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/resource/technical/document/datasheet/08/97/0a/0c/cf/4b/41/40/DM00213876.pdf/files/DM00213876.pdf/jcr:content/translations/en.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.
 
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