AN2818 Freescale Semiconductor / Motorola, AN2818 Datasheet - Page 15

• Manufacturer Part Number: AN2818
• Description: Romeo2 Monitor for the MC68HC908AP64 MCU
• Manufacturer: Freescale Semiconductor / Motorola

Figure 8
(11110000 binary).
Receiving an FSK Message Without Header
Below is an example of receiving an FSK modulated message. The message ID is 0xA5. The data rate
is 1000 bits per second, carrier frequency 434 MHz.
Freescale Semiconductor
1. Set CR1 register to value 0xFA using command CR1 FA <return>
2. Set CR2 (ID register) to 0xa5 using command CR2 a5 <return>.
3. Set CR3 register to value 0x08 using command CR3 08 <return>.
This configures the following bits:
CF = 1 (434 MHz carrier frequency)
MOD = 1 (FSK modulation)
SOE = 1 (strobe oscillator enabled)
SR0/1 = 10 (strobe oscillator ratio — value not important)
DME = 1 (Data Manager Enabled)
HE = 0 (No header in message)
This configures the following bits:
DR1/0 = 00 (1–1.4kBd data rate range)
shows the above setup after reception of a message containing one byte of data with value 0xf0
When receiving messages where the number of data bits is an exact
multiple of eight, Romeo2 may add an extra byte to the end of the message.
Figure 8. Receiving OOK Message Without Header
Romeo2 Monitor for the MC68HC908AP64 MCU, Rev. 0
NOTE
RF Message Formats
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