PIC16F7X Datasheet, PDF (70/174 Pages) Microchip Technology – 28/40-Pin 8-Bit CMOS FLASH Microcontrollers

PIC16F7X
9.3.2 MASTER MODE
Master mode of operation is supported in firmware
using interrupt generation on the detection of the
START and STOP conditions. The STOP (P) and
START (S) bits are cleared from a RESET or when the
SSP module is disabled. The STOP (P) and START (S)
bits will toggle based on the START and STOP condi-
tions. Control of the I²C bus may be taken when the P
bit is set, or the bus is IDLE and both the S and P bits
are clear.
In Master mode, the SCL and SDA lines are manipu-
lated by clearing the corresponding TRISC<4:3> bit(s).
The output level is always low, irrespective of the
value(s) in PORTC<4:3>. So when transmitting data, a
’1’ data bit must have the TRISC<4> bit set (input) and
a ’0’ data bit must have the TRISC<4> bit cleared (out-
put). The same scenario is true for the SCL line with the
TRISC<3> bit. Pull-up resistors must be provided
externally to the SCL and SDA pins for proper opera-
tion of the I²C module.
The following events will cause SSP Interrupt Flag bit,
SSPIF, to be set (SSP Interrupt will occur if enabled):
• START condition
• STOP condition
• Data transfer byte transmitted/received
Master mode of operation can be done with either the
Slave mode IDLE (SSPM3:SSPM0 = 1011), or with the
Slave active. When both Master and Slave modes are
enabled, the software needs to differentiate the
source(s) of the interrupt.
9.3.3 MULTI-MASTER MODE
In Multi-Master mode, the interrupt generation on the
detection of the START and STOP conditions, allows
the determination of when the bus is free. The STOP
(P) and START (S) bits are cleared from a RESET or
when the SSP module is disabled. The STOP (P) and
START (S) bits will toggle based on the START and
STOP conditions. Control of the I²C bus may be taken
when bit P (SSPSTAT<4>) is set, or the bus is IDLE
and both the S and P bits clear. When the bus is busy,
enabling the SSP Interrupt will generate the interrupt
when the STOP condition occurs.
In Multi-Master operation, the SDA line must be moni-
tored to see if the signal level is the expected output
level. This check only needs to be done when a high
level is output. If a high level is expected and a low level
is present, the device needs to release the SDA and
SCL lines (set TRISC<4:3>). There are two stages
where this arbitration can be lost, these are:
• Address Transfer
• Data Transfer
When the slave logic is enabled, the slave continues to
receive. If arbitration was lost during the address trans-
fer stage, communication to the device may be in
progress. If addressed, an ACK pulse will be gener-
ated. If arbitration was lost during the data transfer
stage, the device will need to retransfer the data at a
later time.
TABLE 9-3: REGISTERS ASSOCIATED WITH I²C OPERATION
Address Name
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Value on:
POR,
BOR
Value on
all other
RESETS
0Bh, 8Bh, INTCON
10Bh,18Bh
0Ch
PIR1
8Ch
PIE1
GIE
PEIE TMR0IE INTE RBIE TMR0IF INTF RBIF 0000 000x 0000 000u
PSPIF⁽¹⁾
PSPIE⁽¹⁾
ADIF
ADIE
RCIF
RCIE
TXIF SSPIF CCP1IF TMR2IF TMR1IF 0000 0000 0000 0000
TXIE SSPIE CCP1IE TMR2IE TMR1IE 0000 0000 0000 0000
13h
SSPBUF Synchronous Serial Port Receive Buffer/Transmit Register
93h
SSPADD Synchronous Serial Port (I²C mode) Address Register
xxxx xxxx
0000 0000
uuuu uuuu
0000 0000
14h
SSPCON WCOL SSPOV SSPEN CKP SSPM3 SSPM2 SSPM1 SSPM0 0000 0000 0000 0000
94h
SSPSTAT SMP⁽²⁾ CKE⁽²⁾ D/A
P
S
R/W UA
BF
0000 0000 0000 0000
87h
TRISC PORTC Data Direction Register
1111 1111 1111 1111
Legend: x = unknown, u = unchanged, - = unimplemented locations read as ’0’. Shaded cells are not used by SSP module in I²C mode.
Note 1: PSPIF and PSPIE are reserved on the PIC16F73/76; always maintain these bits clear.
2: Maintain these bits clear in I²C mode.
DS30325B-page 68
 2002 Microchip Technology Inc.