doppelgrau/esp32-f9p-io-board

An IO-PCB (two motor-driver/H-bridge, CAN, RS232, ADS1115, relay, ethernet, ardusimple f9p compatible connector) with an ESP32 for 12V power, three 15V tolerant analog inputs, three 5V tolerant inputs.

ESP32 F9P IO board

This PCB is a versatile IO plattform that provides computing power (ESP32) and IO interfaces to build GPS/RTK applications.

Hardware Overview

• Power supply:
  • Input 9V-28V (labeld 12V on the board), external connection on J4.
  • Protected against wrong polarity (Diode D7 parallel to the relay K1)
  • Reduced inrush current (resistors R15/16 in serie with the starting diode D7 before the relay K1 closes and shortens the path).
  • V78E05-1000 (step down converter) PS1 generates 5V
  • AZ1117-3.3 LDO U2 generates 3V from the 5V supply.
  • 12A (slow) fuse soldered on the board. Recommended to use a 10A external fuse.
• ESP32-WROOM-32 U1 for computing-power, wifi, Bluetooth
• Arduino headers for the simpleRTK2B-F9P (uart 1 of the F9P connected)
• Serial interfaces
  • one uart (IO13/14) on the Arduino headers for the F9P
  • one uart (IO0/2) next to the arduino headers on two pins (J2) for the new simpleRTK2Blight. Since the two pins have a special meaning during boot, pulling TX to GND during startup results in the ESP going into programming mode.
  • one uart (IO15/16) for RS232 on the D-Sub connector J16
  • one uart (IO1/3) on the USB-Uart converter (J14) - Also supports programming with "RTS/DTR"
• I2C (IO32/33)
  • I2C with 3.3V logic level (J8 pin header, J13,17 qwiic connector)
  • I2C with 5V logic level (J7 pin header)
  • internal used adresses:
    • 0x1C - Magnetometer part of the LSM9DS1 (U12)
    • 0x43 - FXL6408 port extender (IC 1)
    • 0x48 - ADS1115 (U4)
    • 0x6A - Accelerometer part of the LSM9DS1 (U12)
• CAN bus
  • Tranceiver (U2) + ESP32 integrated controler (TX IO5, RX IO35)
  • Termination resistor and sending messages can/must both be enabled with a jumper on J12
  • external connection J18
• Ethernet:
  • internal MAC, connected to LAN8720A on IO17,18,19,21,22,23,25,26,27
    • IO17 Clock
    • IO18 MDIO
    • IO23 MDC
  • PHY-Reset controlled with FXL6408-GPI01
  • ETH-Address of the LAN8720: 0
• IMU: 9 Axis, LSM9DS1 (U12). Magnetometer needs iron correction to be usable.
• Outputs
  • One H-bridge/motordriver with two VNH7070AS (U3/5), (PWM IO4, FXL6408-GPIO6/7 direction). External connected on J4
  • One H-bridge/motordriver with one VNH7070AS (U9), (PWM IO12, FXL6408-GPI04/5 direction), external connected on J3
  • One Relay (K2) controlled on FXL6408-GPI03, external connected on J3
  • One status LED (D2) controlled on FXL6408-GPI02
• Inputs
  • Three 15V tolerant (analog) inputs IO34, SENSOR_VN/36, SENSOR_VP/39, external connected on J1
  • Three 5V tolerant (analog) inputs on the ADS1115, first two cann be used to measure differential. Number four is hardwired to VCC/5V. External connected on J5
  • One Button (e.g. for entering configuration mode), on FXL6408-GPI00
• Connectors:
  • J1 - 6 pin PTSM header. 15V tolerant inputs and 12V for easy cabeling if used as switch
  • J2 - 2 Pin Uart
  • J3 - 7 pin PTSM header. Outputs of second H-bridge, two times ground (for using as two half bridges) and the three pins for the relay (comm, no, nc)
  • J4 - 4 pin CCA header. Power input and output of the first motor driver/h-bridge
  • J5 - 5 pin PTSM header. Three ADS1115 inputs, 5V and GND for easy cabeling (e.g. linear potentiometer)
  • J7 - 4 pin header. I2C 5V logic level + GND and 5V
  • J8 - 4 pin header. I2C 3V3 logic level + GND and 3V3
  • J9, J10, J11 - 8 pin header. Socket for the simpleRTK2B F9P
  • J12 - 2x2 horizontal pin header. Used for jumpers to enable CAN termination and/or CAN TX
  • J13, J17 - qwiic connector. I2C 3V3
  • J14 - micro USB connector. Can power 5V and 3V3 part of the PCB. Electricaly not isolated! Used for programming the ESP32
  • J15 - RJ45 ethernet connector
  • J16 - D-Sub connector (male). RS232
  • J18 - 2 pin PTSM header. CAN bus

esp32-f9p-io-board's Issues

Disable power-save mode for RS232

The uart <-> RS232 converter supports a power-safe mode that might cause trouble.
Pull the FORCEON-pin to high instead of gnd

add an other uart for simpleRTK2Blite

To use two ardusimple F9P (simpleRTK2B and simpleRTK2Blite) for RTK + heading with NTRIP a second UART is needed with an interface so it can be connected to the top module.

• If you use an LR kit with corrections coming over XBee, you only need to connect to 1 UART. This UART will give RTK position + heading, but only in UBX protocol
• If you use NTRIP server, you will need 2 connections, one to send corrections to simpleRTK2Blite, and another one to read RTK position+heading in UBX protocol.

Check solder paste stencil

• Same behavior for all connectors
• All pads on USB for better mechanical connection
• maybe less paste for the port multiplier

Case: Basic-1xF9P - Thinner top side

Evaluate if the parts over the LEDs can be made/printed thinner.
If printed with transparent filament it should be more clear and with two color prints it would look nicer.

Fuse for the motors lower and replaceable

Basic-1xF9P: Screws

Some Redesign do allow larger screws, the M2 work but not enough reserves to be comfortable.

Check if the xbee-uart is free

If the xbee-uart is currently connected to the esp32 change to uart2

Better part names/values

Change the part names/values in such a way, all relevant parameters are visible (e.g. for capacitors not only the capacity but also the allowed voltage)

Evaluate the connectors

• More robust for USB?
• Keep the PTSM? If so Change Variant? SMD/THT

Easier to test

Make sure everything can be tested without the need of external cables (using pogo pins)

Basic-1xF9P: holder during installation

Evaluate if there could not be some sort of support on two or three sides, so the pcb is a bit secured during installation.

Check if current monitoring is reasonable

Get two output pins for the slect on the VNH and three analog inputs (or check if two would be enough)

Reduce M1 to one VNH707AS

Evaluate if there are any drawbacks (for usual motors should be more than enough).
If no drawbacks, eliminate or use for additional (digital) outputs

Case: Basic-1xF9P - Slightly rounded outer corners

make the edges a bit less sharp
Round with a small diameter or a 45° cutoff (0.5mm-1mm?)

Update BOM, Gerber, ...

After everything is done, update gerber, bom, ibom, seedstudio files

Better software examples

Provide better examples (maybe libraries?) for:

• IMU iron correction
• IMU gyro correction
• using the port expander
• using the VNH7070

Move "Config" Button

It's very hard to press the Button if a F9P Board is mounted.

Some visual aid to help with IMU orientation

Idea: plane with axes, in software rotate pitch/yaw/roll until plane fly in direction of travel

Fix connection to LAN8720A MDIO

Connection of MDIO is broken, fix it to enable ethernet

Can I do everything with one ESP32?

Hello doppelgrau.
It is a wonderful work!
I want to use this board for NTRIP Client to F9P, and AutoSteer to AgOpenGPS .
Do you think it is possible in ONE esp32?

Check if power supply can be made more robust

adding inductor and supressor diode?

Check optional parts

Check if there is an option to put different IMUs on the board and only populate the requested (MMA, LSM9DS1 ...)

Check IO protection

Related a bit to #37, check if protection against to high/reverse voltage should be improved

Improve Readme

Include a good documentation what the board has / what parts, internal and external inout

Use "Thermal Relief"-Pads for better soldering on pads with low current

physical location of the LSM9DS1

Currently placed near the RS232 connector. but connectors and cables introduce metal in the area that can disturb the magnetic field after calibration.
Maybe better placed under the F9P, magnetic error should be more constant there => after calibration not a huge problem

Basic-1xF9P: Space for cable management / switch position

current position of the switch leaves not enough space for good cable management around the power connector.
So improve free space (top/bottom, wider?) or move power switch

More flash

Evaluate if a ESP32 with more flash is an option, so larger Software can use OTA-Updates

Add some fiducials (>= 3)

Add some fidducials, so a pick & place machine might be used

Evaluate if a three Port switch is an option

Two external Ethernet-connections would make daisy-chainning easier

divide power supply

Divide the power supply of the PCB from the Power suppl to the motor driver.
So the motordriver can be easily driven with an other voltage (e.g. 24V)

stable reference voltage for sensor and analog part of ads1115

some ldo or a reference voltage

Change xbee-Uart Pins

Change the Xbee uart PINs with the pwm pins so there won't be any problems if pulled to gnd during startup
(Test before it not pulled down from the VNH and if PWM s okay)

Update Gerber-Files

including drill files

Rotate PCB Labels

The following labels are inverted relative to others:

• ESP-F9P-IO-Board
• Version 2.2
• GND / 12V / M1A / M1B
• Uart / RX / TX

C35 Capacitance Value

Thank you for answering my question!
I noticed a small point.

In the circuit diagram "C35" is "100nF/16V"
But in "Parts.ods" C35's Mouser Partnumber is "603-CC805KRX7R9BB103"
it's 10nF.

I think Row"C35,C47,D2,D5,D9" Colum"Mouser Partnumber-" is wrong.

SMT-Pads/Holes in stencil

Make sure all SMT-connectors have the Stencil/Paste layer activated for the footprints

PIN for programming mode

README.md

one uart (IO0/2) next to the arduino headers on two pins (J2) for the new simpleRTK2Blight. Since the two pins have a special meaning during boot, pulling RX to GND during startup results in the ESP going into programming mode.

pulling TX to GND ,I think

free GND and Power under IMU

Look again into the datasheet, I think a bit clearance could help

Closer look at CAN-interface

• Improve Termination 2x60 Ohms to Capacitor (one end GND) instead of 120Ohm. Reduces Common Mode Problems
• Check ESD, improve with something like a PESD2CAN

Physical: Mounting hole for the F9P

The front mounting hole to secure the F9P does not fit, movement required

Update Part List

Some removed Parts are still referenced

Isolate USB from the rest

Check if reasonable to isolate the USB from the rest.

Reduce BOM

Tests with the oscilloscope show that the inductor in front of the ADS1115 is not much more effective than the RC in front of the LSM9DS1. So to make the BOM shorter changed the inductor to a resistor.