The design is provided "AS IS", without any warranty of any kind, express or implied, including but not limited to the warranties of merchantability, fitness for a particular purpose and non-infringement. In no event shall the authors or copyright holders be liable for any claim, damages or other liability, whether in an action of contract, tort or otherwise, arising from, out of or in connection with the design or the use or other dealings this product.
This PCB was designed to work with the SensESP Sensor framework specifically for the user with I2C or OneWire sensors. While the design allows for three sensors to be connected on the same PCB, when using I2C SensESP supports only one sensor. When using OneWire, multiple sensors can be used on one PCB.
The PCB works best with Wemos-D1-Mini PRO because the USB connector sits at the top so even if mounted straight on the board, you have enough space to connect a 90-degree USB connector ("Up Angled")
Power can be supplied by:
- USB to Wemos
- Through Buck Converter (MP1584, $2.00 on eBay)
- 5V to P7
Sensor ports:
- J5 (VCC, GND, D1, D2) is connected through the eight switch DIP to three 4-pin headers (J6, J7, J8) which all have VCC, GND, D1 and D2. The J6, J7 and J8 headers are connected in parallel (see dip switches below)
OneWire
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For OneWire, you should use the D1 GPIO pin on the Wemos. So if you are starting with the sample code used this in your SensESP code:
DallasTemperatureSensors* dts = new DallasTemperatureSensors(D1);
Dip Switch:
- D1 - 5V to Wemos Chip On/Off. Using this allows you to measure and adjust the voltage of your buck converter. When doing so - note that the Capacitor will need charging / de-charging for every adjustment made which you can do using a resistor
- D2 - Supply 3.3v to VCC on the headers J6, J7, J8
- D3 - Supply 5v to VCC on the header J6, J7, J8
- D4 - LED on/off
- D5-D8: "Open/Close" J5-> J6, J7, J8 connections. You use these switches if you have a sensor where VCC, GND, D1 (SCL) and D2 (SCA) are not in this order.
If you have a sensor with pinout VCC, GND, SCL, SCA, there is no need to connect anything to J5, instead just close (connected) switches D5-D8 and connect your sensors to J6, J7 or J8.
But if you want to connect an I2C sensor with a different pinout, for example, VCC, GND, SCA and SCL (note SCA and SCL are reversed)
- Open (not connected) switch D7 and D8 (SCA and SCL)
- Manually connect two jumper wires:
- One from Pin 3 on J5 to Pin 4 on J8 and
- One from Pin 4 on J5 to Pin 3 on J8. You have now effectively changed the pinouts on J6, J7 and J8 to VCC, GND, SCA and SCL and can connect your sensor to J6 or J7 (given that J8 contains the jumper wires)
There is a sample image (SensorChangePinout.png) in this folder which shows the above example.
Resistors: R1: 330k for LED R2: 4.7k for OneWire (not used for I2C)
Diodes: 3 x IN5817 Schottky diodes to protect:
- (D6) JP7, 5v going back to MP1584
- (D4) 5v going back to 3.3v pin on Wemos
- (D5) 3.3v going back to 5v pin on Wemos
D4+D5 are there protect from SW1 and SW2 both being open at the same time
Capacitor C3: 470uF / 25v to regulate supply to Wemos.
- Plastic project boxes, bought on eBay (picture enclosed): 5 boxes for £6.00 (£1.20 each)
- Mounting Screws: M3 x 6mm
- Black Plastic Holder Diode / Holder LED Clip Bezel Mount: 3mm or 5mm (depending on LED size): eBay: £0.10 each
- AWG20 Cable for LED + Power
- Heat String for LED
- Dupont Connectors for LED to PCB connection
- I used JLCPCB, but there are many options
- Uploaded (Zipped) Gerber directory to manufacturer to order product
- I paid $2.00 for 5 PCB's plus (cheapest shipping option) $6.29 Shipping. Total $8.29 / 5 = $1.66 per PCB (excluding parts)
- They arrived within two weeks
Gerbers/ Directory with individual Gerber Files Gerbers.zip Zipped Gerber Directory - used to upload to manufacturer Manufacturing.pdf Sample document to show order details PCB Empty and Build.jpg Screenshot of mounted and empty PCB PlasticBox.png Screenshot of the box used to mount the PCB README.txt This file Bill-of-Materials.pdf List of components used on the PCB SensESP.fzz Fritzing file with the PCB Breadboard, Schematic and PCB design