Datasheet
© 2007 Microchip Technology Inc. DS41232D-page 121
PIC12F635/PIC16F636/639
11.32.2 COMMAND
DECODER/CONTROLLER
The circuit executes 8 SPI commands from the MCU.
The command structure is:
Command (3 bits) + Configuration Address (4 bits) +
Data Byte and Row Parity Bit received by the AFE Most
Significant bit first. Table 11-5 shows the available SPI
commands.
The AFE operates in SPI mode 0,0. In mode 0,0 the
clock idles in the low state (Figure 11-19). SDI data is
loaded into the AFE on the rising edge of SCLK and
SDO data is clocked out on the falling edge of SCLK.
There must be multiples of 16 clocks (SCLK) while CS
is low or commands will abort.
TABLE 11-5: SPI COMMANDS (AFE)
Command Address Data
Row
Parity
Description
Command only – Address and Data are “Don’t Care”, but need to be clocked in regardless.
000 XXXX XXXX XXXX X Clamp on – enable modulation circuit
001 XXXX XXXX XXXX X Clamp off – disable modulation circuit
010 XXXX XXXX XXXX X Enter Sleep mode (any other command wakes the AFE)
011 XXXX XXXX XXXX X AGC Preserve On – to temporarily preserve the current AGC level
100 XXXX XXXX XXXX X AGC Preserve Off – AGC again tracks strongest input signal
101 XXXX XXXX XXXX X Soft Reset – resets various circuit blocks
Read Command – Data will be read from the specified register address.
110 0000 Config Byte 0 P General – options that may change during normal operation
0001 Config Byte 1 P LCX antenna tuning and LFDATA output format
0010 Config Byte 2 P LCY antenna tuning
0011 Config Byte 3 P LCZ antenna tuning
0100 Config Byte 4 P LCX and LCY sensitivity reduction
0101 Config Byte 5 P LCZ sensitivity reduction and modulation depth
0110 Column Parity P Column parity byte for Config Byte 0 -> Config Byte 5
0111 AFE Status X AFE status – parity error, which input is active, etc.
Write Command – Data will be written to the specified register address.
111 0000 Config Byte 0 P General – options that may change during normal operation
0001 Config Byte 1 P LCX antenna tuning and LFDATA output format
0010 Config Byte 2 P LCY antenna tuning
0011 Config Byte 3 P LCZ antenna tuning
0100 Config Byte 4 P LCX and LCY sensitivity reduction
0101 Config Byte 5 P LCZ sensitivity reduction and modulation depth
0110 Column Parity P Column parity byte for Config Byte 0 -> Config Byte 5
0111 Not Used X Register is readable, but not writable
Note: ‘P’ denotes the row parity bit (odd parity) for the respective data byte.