SPI Packets

Host-to-Decoder Packet Descriptions

Table B-3 Checksum Packet Bit Assignments

Configuration Packet

The Configuration Packet defines a number of different configuration options for the FLEXchip IC. The FLEXchip IC ignores this packet when decoding is enabled (i.e., the ON bit in the Control Packet is set). The ID of the Configuration Packet is 1.

Table B-4 Configuration Packet Bit Assignments

OSCILLATOR FREQUENCY DIFFERENCE (OFD)

These bits describe the maximum difference in the frequency of the 76.8 kHz oscillator crystal with respect to the frequency of the transmitter. These limits should be the worst case difference in frequency due to all conditions, including but not limited to aging, temperature, and manufacturing tolerance. Using a smaller frequency difference in this packet will result in lower power consumption due to higher receiver battery save ratios. Note that this value is not the absolute error of the oscillator frequency provided to the FLEXchip IC. The absolute error of the clock used by the FLEX transmitter must be taken into account. (If the transmitter tolerance is ±25 ppm and the 76.8 kHz oscillator tolerance is ±140 ppm, the oscillator frequency difference is ±165 ppm and OFD should be set to 0.)The value after reset = 0. Table B-5 on page B-9 summarizes the bit definitions.