What About The SUB-D Connector On XL
In addition to the PS/2 connector which should be used for I2C and test pin connection as the default connector, Tracii XL provides a SUB-D 15 connector for future extensions and special applications. We do not encurage users to make use of this connector in standard applications but since we receive so many questions about it we think it’s time to demystify those 15 magic pins.
| SUB-D15 PIN | Description |
|---|---|
| 01 | Testpin out 1 |
| 02 | Testpin out 0 |
| 03 | Testpin in 1 |
| 04 | Testpin in 0 |
| 05 | I2C-bus: SDA |
| 06 | I2C-bus: SCL |
| 07 | I2C-bus: GND |
| 08 – 14 | Reserved |
| 15 | I2C-bus: VCC |
Note that I2C VCC needs to be supplied by the external I2C bus (1.2-6V) as a reference voltage.
But one secret remains: What are the reserved pins good for?
Tracii XL was designed as a future proof platform and as such it is equipped with various extra facilities for enhancements and custom applications. These may not even be I2C related but may include things like support of other bus systems, industrial automation control, event triggering etc. These future applications may show the need for additional connectors and we want to avoid modifications of the XL case for such purpose.
So, there are not only reserved pins visible on the outside – there is also more to come inside.