SPRUJ79 November 2024 F29H850TU , F29H859TU-Q1
The short serial message format uses multiple fast SENT data frames to transmit slow data. While the fast data is transmitted through each single SENT frame, the slow data is transmitted using bit 2 of the status and communication nibble pulse, with the most-significant bit first. The serial data is communicated in a 16-bit sequence. This means that after 16 SENT frames are received correctly, there is a 4-bit message ID, an 8-bit slow data, and a 4-bit CRC. The start bit of the serial message is indicated by a 1 in bit 3 of the status and communication nibble pulse, and the subsequent 15 frames must have a status bit 3 which is 0.
The 16-bit message contains a 4-bit message ID nibble, 2 nibbles of data, and a CRC nibble. The CRC checksum is derived from the message ID and 2 data nibbles.
The message ID indicates the type of data in the data byte, which is ordered most-significant bit first.
| Message ID | Sensed Value for Data Field |
|---|---|
| 0000 | High Byte of Air Temperature |
| 0001 | Low Byte of Air Temperature |
| 0010 | High Byte of Humidity |
| 0011 | Low Byte of Humidity |
| 0100 | High Byte of Barometric Pressure Data |
| 0101 | Low Byte of Barometric Pressure Data |
| 0110-1110 | Reserved |
| 1111 | Error Codes |