PIC18F2420 MICROCHIP [Microchip Technology], PIC18F2420 Datasheet - Page 187

• Manufacturer Part Number: PIC18F2420
• Description: 28/40/44-Pin Enhanced Flash Microcontrollers with 10-Bit A/D and nanoWatt Technology
• Manufacturer: MICROCHIP [Microchip Technology]

17.4.6
Master mode is enabled by setting and clearing the
appropriate SSPM bits in SSPCON1 and by setting the
SSPEN bit. In Master mode, the SCL and SDA lines
are manipulated by the MSSP hardware.
Master mode of operation is supported by interrupt
generation on the detection of the Start and Stop con-
ditions. The Stop (P) and Start (S) bits are cleared from
a Reset or when the MSSP module is disabled. Control
of the I
bus is Idle, with both the S and P bits clear.
In Firmware Controlled Master mode, user code
conducts all I
Stop bit conditions.
Once Master mode is enabled, the user has six
options.
1.
2.
3.
4.
5.
6.
FIGURE 17-16:
 2004 Microchip Technology Inc.
Assert a Start condition on SDA and SCL.
Assert a Repeated Start condition on SDA and
SCL.
Write
transmission of data/address.
Configure the I
Generate an Acknowledge condition at the end
of a received byte of data.
Generate a Stop condition on SDA and SCL.
SDA
SCL
2
C bus may be taken when the P bit is set, or the
MASTER MODE
to
2
C bus operations based on Start and
the
2
C port to receive data.
SSPBUF
MSSP BLOCK DIAGRAM (I
SDA In
Bus Collision
SCL In
register
Read
initiating
MSb
PIC18F2420/2520/4420/4520
Write Collision Detect
end of XMIT/RCV
Start bit, Stop bit,
State Counter for
Clock Arbitration
Acknowledge
Stop bit Detect
Start bit Detect
SSPBUF
Generate
SSPSR
Preliminary
2
C MASTER MODE)
LSb
Write
The following events will cause the SSP Interrupt Flag
bit, SSPIF, to be set (SSP interrupt, if enabled):
• Start condition
• Stop condition
• Data transfer byte transmitted/received
• Acknowledge transmit
• Repeated Start
Clock
Data Bus
Shift
Note:
Internal
Set/Reset, S, P, WCOL (SSPSTAT)
Set SSPIF, BCLIF
Reset ACKSTAT, PEN (SSPCON2)
The MSSP module, when configured in
I
of events. For instance, the user is not
allowed to initiate a Start condition and
immediately write the SSPBUF register to
initiate transmission before the Start condi-
tion is complete. In this case, the SSPBUF
will not be written to and the WCOL bit will
be set, indicating that a write to the
SSPBUF did not occur.
2
C Master mode, does not allow queueing
SSPM3:SSPM0
SSPADD<6:0>
Generator
Baud
Rate
DS39631A-page 185