Tecla Access/Shield Proto II
From IDRC Mobile Wiki
The Tecla Access Shield is a device that enables connection of powered wheelchairs and external switches to Bluetooth-enabled devices. The information herein should be sufficient to create client applications for the Tecla Access Shield on any Bluetooth-enabled device supporting the SPP/RFCOMM protocol. If you require additional information, please contact us.
Contents |
Features
- Up to six binary switch inputs
- 4 inputs through DE9 male header compatible with:
- 2 inputs through standard 3.5mm female stereo plug compatible with:
- Implements one passive filter per switch to eliminate metal plaque noise
Technical Specifications
- Switches normally open (HIGH), closing to common (LOW).
- Bluetooth switch events broadcasted through virtual serial port using the serial port profile (SPP/RFCOMM) at a 115200 baud rate.
Switch Event Anatomy
Once a device establishes a SPP/RFCOMM connection with the Tecla Access Shield, it will receive a byte on every switch state change. This byte will contain the state of all switches connected to the Tecla Access Shield, according to the following table:
| Bit | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
|---|---|---|---|---|---|---|---|---|
| Name | - | - | E2 | E1 | J4 | J3 | J2 | J1 |
| Initial Value | 0 | 0 | 1 | 1 | 1 | 1 | 1 | 1 |
| Port | - | - | Dual | Dual | ACU/ECU | ACU/ECU | ACU/ECU | ACU/ECU |
| Pin | - | - | ring | tip | 4 | 3 | 2 | 1 |
Bits 0..3 – J1..4
Up to four (4) generic switch inputs connected to DE9 male header on Tecla Access Shield. Follows the standard configuration of wheelchair ACU/ECUs. Typically assigned to directional (i.e., forwad, backward, right & left) actions in wheelchair joysticks or adapted switches.
Bits 4..5 – E1..2
Up to two (2) generic switch inputs connected to 3.5mm stereo plug on Tecla Access Shield. Follows the standard configuration of ability switches.
Echoing function
The Tecla Access Shield includes an echoing function that allows for connections to be monitored from a client device. Any character sent to the Tecla Access Shield will be immediately echoed as long as there is a stable connection. The use of a character that cannot be confused with switch events (e.g., 0x70) is recommended.
