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A BLE stopwatch for inline speed slalom or whatever like that

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Open speedomenter WIP

OSOM (read as ˈôsəm) is the acronym of Open Speedometer.

Architecture

The new architecture is the following:

Clinet <==BLE==> Master <==2.4GHz==> Slave

where:

  • Master: CC2541 <==UART==> PIC <==SPI==> nRF24L01+
  • Slave: PIC <==SPI==> nRF24L01+

The client is a device that must be compatible with BLE (Bluetooth 4.x).

The CC2541 (aka NP, aka Network Processor) will run a standard firmware that is in charge of providing a bluetooth connection to the PIC.

Master and Slave will exchange messages over a custom, light-weight, protocol.

Specifications

  • Microcontroller: PIC32MX274F256D @72MHz (TODO verify)
  • Communication:
    • Bluetooth (master only): HM10 Bluetooth 4.2 Low Energy
    • Wireless: nRF24L01+ @2.4GHz
  • Power:
    • LiPo 1s Battery, 1200/2000 mAh (not choosen yet)
    • 5V provided by micro USB, 500 mA MAX
  • Sensor: custom made 650nm modulated laser sensor
  • Laser source: Red diode laser, 650nm @5mW

PIC PIN assignment

Bluetooth (master only)

PIN I/O PPS Function Note
6 IN RPB2 U1RX PIC <== NP
7 OUT RPB3 U1TX PIC ==> NP

nRF24L01+

PIN I/O PPS Function Note
21 IN RPB10 INT1 Interrupt generated by nRF24L01+
22 OUT RPB11 SDO2
23 OUT - CS RB12
24 IN RPB13 SDI2
25 OUT - CE RB14
26 OUT RPB15 SCK2

Debug

PIN I/O PPS Function Note
4 OUT RPB0 U2TX PIC ==> PC
5 IN RPB1 U2RX PIC <== PC

USB will be available too, with at least a comunication device class (CDC) enumeration.

Sensing

PIN I/O PPS Function Note
16 IN - INT0 Left IN Interrupt
11 IN RPB4 INT4 Right IN Interrupt

Battery Charger

New PIC analisys required

LEDs

Analisys required.

Note

  1. Master only: an extra LED from CC2541 indicates the BT connection status.
  2. From the battery charger an extra LED indicates che charging status.

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A BLE stopwatch for inline speed slalom or whatever like that

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