AN2818 Freescale Semiconductor / Motorola, AN2818 Datasheet - Page 18

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

RF Message Formats
Receiving Data Without Manchester Encoding
The Romeo2 monitor can be used to configure Romeo2 to receive RF data not encoded using
Manchester encoding. To do this, Romeo2's Data Manager should be disabled (set DME bit to logic 0)
However, this data will not be displayed correctly on the terminal screen. The user should use an
oscilloscope on Romeo2's MOSI pin to monitor the data.
For example, to receive data in different encoding formats at 434 MHz, OOK modulation:
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1. Set CR1 register to value 0xD8 using command CR1 DA <return>.
2. Set CR3 register to value 0x48 using command CR3 48 <return>.
3. Set LNA pin to logic 1 using command LNA 1 <return>.
4. Set STROBE pin to logic 1 using command STROBE 1 <return>.
This configures the following bits:
CF = 1 (434 MHz carrier frequency)
MOD = 0 (OOK modulation)
SOE = 1 (strobe oscillator enabled)
SR0/1 = 10 (strobe oscillator ratio — value not important)
DME = 0 (Data Manager Enabled)
HE = 0 (No header in message)
This configures the following bits:
DR1/0 = 01 (2–2.7kBd data rate range)
MG = 0 (normal mixer gain)
MS = 0 (mixout pin set to mixer output)
PG = 1 (phase comparator gain = low gain mode)
Figure 10. Receiving Message With Header FIeld
Romeo2 Monitor for the MC68HC908AP64 MCU, Rev. 0
Freescale Semiconductor