I wanted to share 2 different PCB designs targeted primarily towards using a SimpleRTK2B Micro F9P as a base station.
First the SimpleRTK2B-Micro-breakout-board.
It’s a small board with a USB port, you can use it with a raspberry Pi, Orange Pi, Banana Pi, Windows, whatever has a USB port.
All of the Micro F9P pins are broken out to 0.1" spaced pads, so if you want to you can add headers and use the board on a breadboard, connect to the hardware serial, power it externally, etc.
You can purchase the board fully assembled from JLCPCB using their SMT service.
All the files are here:
Next is the simpleRTK2B-Micro-Hat-for-Raspi.
This board connects the Micro F9P’s UART1 to the Pi’s UART 1. There’s no USB cable required for normal operation if you setup your software for UART.
A USB port is included in case you want to program the Micro F9P using U-Center.
All of the Micro F9P pins are broken out to 0.1" spaced pads, and the Pi’s 40 pin header is duplicated as well. You can experiment with I2C OLED screens, adding switches, etc.
Or experiment with PoE, passive PoE is very easy to add with a voltage regulator. I added PoE to mine, but of course you can also power the Pi over USB like normal.
You can buy the board almost fully assembled from JLCPCB. You’ll have to source and solder the 40 pin header that mates with the Pi yourself.
All the files are here:
Do you normally use a POE adapter? or can you get 802.3af power right off the Pi?
Not sure how many UARTs are easily available on the standard Pi header, but if a board could supply 1 amp, would be nice to have an xbee slot on the hat for a radio transmitter as well.
I’ve always liked the idea of using RC power regulators. Good reliable power in my experience.
Very cool stuff!
The Pi3B+ and Pi4B break out the 4 “unused” ethernet wires to a 4 pin header. I just connected a UBEC between those pins and the 5v rail.
There’s only one good Pi UART. There’s some software uarts I think, I havn’t played with those.
The Micro F9P has 2 UARTs, the xbee could be connected to the second UART. I don’t know if there is quite enough room on the board for an xbee or if its ok to mount an xbee so close to the F9P. I did break out that second UART to 4 pin headers for an external radio if someone wanted to connect a radio with wires.
With RTKBase you can also use a RTCM serial service, so you could plug a radio into the Pi’s USB port and send messages to the radio that way.
Very good. I’m sure any Pi clone would have to be checked to determine if that’s the same.
I’ve also been buying 802.3af power adapters that split out to USB power micro or mini connectors. They are pretty cheap on AliExpress and work pretty well. I think they can supply an amp. Not sure how much power the Pi’s 3.3v regulator can supply, so still a good idea to power the hat through some kind of external regulator, even if it is from the same 5V supply.
But you’re talking about passive POE here.
Yes USB works fine, although the latest USB to xbee adapter I bought only can supply 300 mA, so it’s not enough to run a 1 watt base station, but I think I can bodge a bigger regulator onto it.
Very good work on this board. I may have to order one. I’d like to setup a complete backup base station that’s ready to plug in and go should anything happen to my active one. Need a bit of redundancy should something happen to me leaving everyone else in the lurch.
When I try to upload the BOM and CPL files to JCLPCB I get an error message.
The below parts won’t be assembled due to data missing.
J1,J2,H1 designators don’t exist in the BOM file.”
It should be safe to continue past that warning. Those parts exist in the schematic but are intentionally left off the BOM. They are just there to put pads in the right place and then you can solder in headers if you ever want to. Just make sure that the JLC preview contains the 2 F9P headers and other parts and then you should be good.
If you want to wait a little longer I’ve made an updated version. Its being made right now and once I’ve tested it I will release it. The size of the breakout board coincidentally happened to be perfect to fit a ~$4 HC05/HC06 bluetooth module to the back, but the pinout order on the breakout board was incorrect to do that. The new design is basically the same, but those 5 pads opposite the USB connector become 6 pads in a different order.
Here’s such a bluetooth module held up to a breakout board. I’ve tested it with jumper wires and the range was about ~30’ outdoors. It should be slick to use with a USB battery bank to map field boundaries on the ATV. I’m 3d printing an enclosure to hold all those bits together right now.
Could you even get the HC05 assembled at JLC? Would have to probably be SMD though
You probably could, but to fit on the board it would have to be double sided SMD and that double sided assembly fee is hefty. This was more of an engineering by inventory thing and the change needed was so small that it felt like a missed opportunity.
EDIT: The HC05 modules are pretty outdated too, and have never been supported by iPhone. If assembling with SMD then a BLE version would probably be better.
Thanks for the swift reply. I have decided to wait for the release of your new design. Easier connection to a bluetooth module sounds fantastic.