Uplift Desk Automation

Message Syntax

A transmitted message has the following syntax.

0xF1, 0xF1, <cmd>, 0x00, <crc>, 0x7E

A received message has the following syntax.

0xF2, 0xF2, <cmd>, <len>, <data...>, 0x0F, <crc>, 0x7E

0xF2, 0xF2 indicates the message start
cmd is one of:
- 0x01 - Height value
- 0x25 - Preset 1 height
- 0x26 - Preset 2 height
- 0x27 - Preset 3 height
- 0x28 - Preset 4 height
len indicates how many messages will be sent next, excluding the CRC and EOT.
data will contain the incoming data values, explained for height readings below.
0x0F - Unknown
crc will be the sum of bytes at index 2 up to the CRC.
0x7E indicates the end of message.

When a new height value comes in, the message will look something like this:

0xF2, 0xF2, 0x01, 0x03, 0x01, 0x1B, 0x0F, 0x2F, 0x7E

In this case, the desk was at 28.3". Here is how we can calculate that.

First off, the command is 0x01, so we know we're about to receive height data.
The next byte tells us to listen for 3 data bytes.
The relevant data comes in as 0x01, 0x1B. This will be converted to a height value later. (Unclear what 0x2F does here)
Then, we add all of the previous bytes (other than the header) to verify the CRC is correct.
0x01 + 0x03 + 0x01 + 0x1B + 0x0F = 0x2F
The actual height is a two-byte word, so the first number needs to be bitshifted. In this example, we received 0x01, 0x1B, so the height calculation looks like: 0x01 << 8 | 0x1B = 283.

Divide the received value by 10 to convert to inches. The result is 283 / 10.0 = 28.3in.