16F876 Microchip Technology, 16F876 Datasheet - Page 79

• Manufacturer Part Number: 16F876
• Description: 28/40-pin 8-Bit CMOS FLASH Microcontrollers
• Manufacturer: Microchip Technology

9.2.9
To initiate a START condition, the user sets the start
condition enable bit, SEN (SSPCON2<0>). If the SDA
and SCL pins are sampled high, the baud rate genera-
tor is re-loaded with the contents of SSPADD<6:0> and
starts its count. If SCL and SDA are both sampled high
when the baud rate generator times out (T
SDA pin is driven low. The action of the SDA being
driven low while SCL is high is the START condition,
and causes the S bit (SSPSTAT<3>) to be set. Follow-
ing this, the baud rate generator is reloaded with the
contents of SSPADD<6:0> and resumes its count.
When the baud rate generator times out (T
SEN bit (SSPCON2<0>) will be automatically cleared
by hardware. The baud rate generator is suspended
leaving the SDA line held low, and the START condition
is complete.
FIGURE 9-12: FIRST START BIT TIMING
1999 Microchip Technology Inc.
I
TIMING
2
C MASTER MODE START CONDITION
Write to SEN bit occurs here.
SDA
SCL
BRG
BRG
SDA = 1,
SCL = 1
T
), the
), the
BRG
Set S bit (SSPSTAT<3>)
T
S
BRG
At completion of start bit,
Hardware clears SEN bit
9.2.9.1
If the user writes the SSPBUF when an START
sequence is in progress, then WCOL is set and the
contents of the buffer are unchanged (the write doesn’t
occur).
and sets SSPIF bit
Note:
Note:
T
Write to SSPBUF occurs here
BRG
1st Bit
If at the beginning of START condition the
SDA and SCL pins are already sampled
low, or if during the START condition the
SCL line is sampled low before the SDA
line is driven low, a bus collision occurs, the
Bus Collision Interrupt Flag (BCLIF) is set,
the START condition is aborted, and the
I
WCOL STATUS FLAG
Because queueing of events is not
allowed, writing to the lower 5 bits of
SSPCON2 is disabled until the START
condition is complete.
2
C module is reset into its IDLE state.
T
BRG
PIC16F87X
2nd Bit
DS30292A-page 79