Datasheet

 2010 Microchip Technology Inc. DS41303G-page 213
PIC18F2XK20/4XK20
17.4.3.4 SSP Mask Register
An SSP Mask (SSPMSK) register is available in I
2
C
Slave mode as a mask for the value held in the
SSPSR register during an address comparison
operation. A zero (‘0’) bit in the SSPMSK register has
the effect of making the corresponding bit in the
SSPSR register a “don’t care”.
This register is reset to all ‘1’s upon any Reset
condition and, therefore, has no effect on standard
SSP operation until written with a mask value.
This register must be initiated prior to setting
SSPM<3:0> bits to select the I
2
C Slave mode (7-bit or
10-bit address).
The SSP Mask register is active during:
• 7-bit Address mode: address compare of A<7:1>.
• 10-bit Address mode: address compare of A<7:0>
only. The SSP mask has no effect during the
reception of the first (high) byte of the address.
REGISTER 17-7: SSPMSK: SSP MASK REGISTER
R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1
MSK7 MSK6 MSK5 MSK4 MSK3 MSK2 MSK1 MSK0
(1)
bit 7 bit 0
Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown
bit 7-1 MSK<7:1>: Mask bits
1 = The received address bit n is compared to SSPADD<n> to detect I
2
C address match
0 = The received address bit n is not used to detect I
2
C address match
bit 0 MSK<0>: Mask bit for I
2
C Slave mode, 10-bit Address
(1)
I
2
C Slave mode, 10-bit Address (SSPM<3:0> = 0111):
1 = The received address bit 0 is compared to SSPADD<0> to detect I
2
C address match
0 = The received address bit 0 is not used to detect I
2
C address match
Note 1: The MSK0 bit is used only in 10-bit slave mode. In all other modes, this bit has no effect.