PIC16F631/677/685/687/689/690
The sequence of events for 10-bit address is as
follows, with steps 7-9 for slave-transmitter:
13.12.1 ADDRESSING
Once the SSP module has been enabled, it waits for a
Start condition to occur. Following the Start condition,
the 8-bits are shifted into the SSPSR register. All
incoming bits are sampled with the rising edge of the
clock (SCL) line. The value of register SSPSR<7:1> is
compared to the value of the SSPADD register. The
address is compared on the falling edge of the eighth
clock (SCL) pulse. If the addresses match, and the BF
and SSPOV bits are clear, the following events occur:
1. Receive first (high) byte of address (bits SSPIF,
BF and bit UA (SSPSTAT<1>) are set).
2. Update the SSPADD register with second (low)
byte of address (clears bit UA and releases the
SCL line).
3. Read the SSPBUF register (clears bit BF) and
clear flag bit SSPIF.
4. Receive second (low) byte of address (bits
SSPIF, BF and UA are set).
a) The SSPSR register value is loaded into the
SSPBUF register.
5. Update the SSPADD register with the first (high)
byte of address; if match releases SCL line, this
will clear bit UA.
b) The buffer full bit, BF is set.
c) An ACK pulse is generated.
6. Read the SSPBUF register (clears bit BF) and
clear flag bit SSPIF.
d) SSP interrupt flag bit, SSPIF of the PIR1 register
is set (interrupt is generated if enabled) on the
falling edge of the ninth SCL pulse.
7. Receive repeated Start condition.
8. Receive first (high) byte of address (bits SSPIF
and BF are set).
In 10-bit Address mode, two address bytes need to be
received by the slave (Figure 13-8). The five Most
Significant bits (MSbs) of the first address byte specify
if this is a 10-bit address. Bit R/W (SSPSTAT<2>) must
specify a write so the slave device will receive the
second address byte. For a 10-bit address, the first
byte would equal ‘1111 0 A9 A8 0’, where A9and
A8are the two MSbs of the address.
9. Read the SSPBUF register (clears bit BF) and
clear flag bit SSPIF.
TABLE 13-3: DATA TRANSFER RECEIVED BYTE ACTIONS
Status Bits as Data
Set bit SSPIF
(SSP Interrupt occurs
if enabled)
Generate ACK
Transfer is Received
SSPSR → SSPBUF
Pulse
BF
SSPOV
0
0
0
1
1
Yes
No
No
No
Yes
No
No
No
Yes
Yes
Yes
Yes
1
1
0
Note:
Shaded cells show the conditions where the user software did not properly clear the overflow condition.
© 2007 Microchip Technology Inc.
DS41262D-page 185
MICROCHIP [ MICROCHIP ]
