The goal is to get a cheap Meshtastic node with this chip, therefore some corners where cut.
Several componemts are implemented double, just pick what works best for you.
- Add CheapMesh variant to Meshtastic firmware
- Option A: use the onboard antennas
- Option B: use an external antenna with the IPEX connector (and cutting of the onboard lora antenna)
- Option C: use an external antenna with an sma connector (and cutting of the onboard lora antenna)
- Option D: solder on a dipol antenna (and cutting of the onboard lora antenna)
- Completele optional. Make sure to get a screen with the matching pinout. I recommend SSD1306 128x64 I2C
- Option A: use an external 3.3V powersource
- Option C: use a AP211K-3.3 and the correspondending capacitors
- Option B: use a L78L33 and the correspondending capacitors
- Option D: use a L78L33 pin compatible DC/DC Buck converter like this one
- Option A: populate the UMH3N
- Option B: use an external usb serial interface which can reset the chip
- Option C: Connect GND and HT_EN with a wire. Power on the board (by plugging in) and remove the wire.
Never connect more than one powersource at a time!!!
- via the usb a pcb connector
- via the usb c connector
- via the Vin Pins
- via the 3.3V Pins
All Resitors are 1206 SMD Resistors
R1, R2: Pullup Resistors, 10kOhm
R3, R4: USB Inline Resistors, zero-Ohm
R5, R6: USB-C Resistors, 5,1kOhm
If you want to flash and reflash the HT-CT62 on the pcb, you need to populate R1 and R2. If you not wanna flash the HT-CT62 on the pcb (you have a already programmed chip), you can make a solder bridge on R1.
- Source the the pcb yourself.
- Solder on the components.
- Flash the ESP.
- Option A - use an external usb serial interface like CH34X, CP21XX, FTDI or any other serial interface.
- Option B - use the usb A pcb port
- Option C - use the usb c port (Need to solder it)
| Reference | Value | Footprint | Qty |
|---|---|---|---|
| AE1,AE2 | Antenna | 2 | |
| C1,C5 | C_Polarized | Depending on power source, +uF if it's instable, optionnal | 2 |
| C3,C6 | C | 0805 or 2012 metric, value depens on your LDO choice | 2 |
| H2,H3 | MountingHole_Pad | 3.2mm M3 DIN965 | 2 |
| J1 | Conn_01x02_Pin | Standard 2.54mm headers | 2 |
| J2 | Conn_01x09_Pin | Standard 2.54mm headers | 9 |
| J4 | USB_C | TYPE-C-31-M-12 | 1 |
| J5 | Conn_Coaxial | SMA 73251-2120 | 1 |
| Q1 | UMH3N | SOT-363 | 1 |
| R1,R2 | 10kΩ | 1206 or 3216 metric | 2 |
| R3,R4 | 0Ω SHUNT | 1206 or 3216 metric | 2 |
| R5,R6 | 5.1kΩ | 1206 or 3216 metric | 2 |
| Screen1 | Conn_01x04_Pin | Standard 2.54mm headers | 4 |
| IO02 | Conn_01x01_Pin | Standard 2.54mm headers | 1 |
| U1 | L78L33 | TO-220-3 | 1 |
| U2 | HT-CT62 | MCU + RF Module: Heltec HT-CT62 | 1 |
| U3 | AP2112K-3.3 | SOT-23-5 | 1 |
CheapMesh by PaulHausK is licensed under Creative Commons Attribution-ShareAlike 4.0 International
