AN2818 Freescale Semiconductor / Motorola, AN2818 Datasheet - Page 12

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

RF Message Formats
MS
Description: MS allows the user to set the value of the Mixout Pin Select bit (MS) in register CR3 on
ROMEO2. The bit can be set to logic 1 or logic 0.
MS 1 <return> — Set MS bit to logic 1
MS 0 <return> — Set MS bit to logic 0
PG
Description: PG allows the user to set the value of the Phase Comparator Gain (PG) bit in register CR3
on ROMEO2. The bit can be set to logic 1 or logic 0.
PG 1 <return> — Set PG bit to logic 1
PG 0 <return> — Set PG bit to logic 0
STOP
Description: STOP puts the MC68HC908AP64 MCU into its low power STOP mode. This allows the user
to make current measurements of the system. To restart the MCU, press the reset button on the
MC68HC908AP64 Demo Board.
RECEIVE
Description: RECEIVE configures the system to receive and display RF messages. The reset pin on the
Romeo2 RF module is set to logic 1. If Romeo2 receives RF data using any of the data format listed in
the Romeo2 data sheet, these will be passed to the MC68HC908AP64 via Romeo2's SPI interface. The
MC68HC908AP64 will pass these messages to the terminal program via its serial port. Examples of the
RECEIVE command usage are given in the following sections. Pressing the return key will stop the
reception of messages.
RECEIVEOFF
Description: RECEIVEOFF stops Romeo2 send RF messages to the display. The reset pin is configured
as an output set to logic 0.
RF Message Formats
The Romeo2 monitor allows the user to receive messages using the data formats defined in the Romeo2
data sheet. There are two basic formats: messages with a header field and messages without a header
field.
Figure 6
shows some basic messages following these formats.
Romeo2 Monitor for the MC68HC908AP64 MCU, Rev. 0
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