Speedometer with ATtiny85 and OLED display

7 months ago 942
  • Description
  • Documents
  • BOM
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Description

Compact speedometer with OLED display and temperature measurement. It features an ATtiny85 uC with USB programming and battery charging and protection circuitry. I will be using it to measure the speed of my bicycle and determine the temperature around me on my rides. The project consists of 2 pcbs: the sensor that will be mounted on the wheel of my bike and the actual speedometer. The wheel sensor sends radio pulses via the H34A transmitter module each time a magnet passes through the Reed sensor. Each pulse will be then received by the H3V4F 433MHz receiver integrated in the speedometer board. The ATtiny85 uC calculates the speed of the wheel and constantly reads the temperature using the TC74A sensor which then prints the values on the oled screen. It can be programmed using the USB interface. The uC can also read the battery voltage. The speedometer circuitry will be supplied with a LiPo battery. The charging and protection circuits are based on a LiPo USB charger board commonly found on Aliexpress. I also thought of replacing the TC74A sensor with a more professional BME280 IC from BOSCH which measures temperature, humidity and altitude, but I did haven't played with it much. This alternative still remains here though.

Documents

Schematic

Speedometer

BOM

ID Designator Footprint Quantity
1 D1 SOD-323 1
2 R1 0805 1
3 C4,C5 0603 2
4 U5 REED-RELAY-L14-2P 1
5 XC6206P332MR,XC6206P1MR SOT-23(SOT-23-3) 2
6 Q3,Q1 SOT-23-3 2
7 C2 0805 1
8 U4 H3V4F-433M 1
9 R11 0805 1
10 C3 0805 1
11 R5,R6,R7,R8 0805 4
12 SW2,SW1 KEY-TOUCH-SMD-6.0*3.5*H 2
13 C8 CASE-C_6032 1
14 R4,R16,R17 0805 3
15 R9 0805 1
16 R10,R18,R19,R20,R12,R15 0805 6
17 R13 0805 1
18 R14 0805 1
19 U7 H34A 1
20 P3,P1 HDR-1X1/2.54 2
21 U2 SOIC-8_208MIL 1
22 D4 SOD-128_L3.7-W2.5-LS4.7-RD 1
23 USB1 MICRO-USB-16 1
24 LED1 LED-0805 1
25 C6 0805 1
26 C7 0805 1
27 R2,R3 0805 2
28 U3 SOT-23-6 1
29 C1 0805 1
30 Q2 TSSOP-8_3X4.4X065P 1
31 U9 OLED 1
32 U1 SOP-8_L4.9-W3.9-P1.27-LS6.0-BL-EP 1
33 C21,C9 0805 2
34 C24 0805 1

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Comments (1)

oleg.tchurilo Reply

Hello. And where is the firmware file ???

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