Multi-Master IIC Interface (MMIIC)
14.3 I/O Pins
The MMIIC module uses two I/O pins, shared with standard port I/O pins. The full name of the MMIIC I/O
pins are listed in Table 14-1. The generic pin name appear in the text that follows.
The SDA and SDL pins are open-drain. When configured as general purpose output pins (PTB0 and
PTB1), pullup resistors must be connected to these pins.
Table 14-1. Pin Name Conventions
MMIIC Generic Pin Names:
Full MCU Pin Names:
PTB0/SDA
Pin Selected for MMIIC Function By:
SDA
SCL
MMEN bit in MMCR1 ($0049)
PTB1/SCL
Addr.
Register Name
Bit 7
MMAD7
1
6
MMAD6
0
5
4
3
MMAD3
0
2
MMAD2
0
1
Bit 0
Read:
Write:
Reset:
Read:
Write:
Reset:
MMAD5
MMAD4
MMAD1 MMEXTAD
MMIIC Address Register
(MMADR)
$0048
$0049
$004A
$004B
$004C
$004D
$004E
$004F
1
0
0
0
0
0
0
MMCLRBB
0
MMCRCBYTE
MMEN
0
MMIEN
0
MMTXAK REPSEN
MMIIC Control Register 1
(MMCR1)
0
MMAST
0
0
MMRW
0
0
0
0
0
0
Read: MMALIF MMNAKIF
MMBB
MMCRCEF
Unaffected
MMIIC Control Register 2
(MMCR2)
Write:
0
0
0
0
Reset:
0
0
0
Read: MMRXIF
MMTXIF MMATCH MMSRW MMRXAK MMCRCBF MMTXBE MMRXBF
0
MMIIC Status Register
(MMSR)
Write:
Reset:
Read:
0
0
0
0
0
1
0
1
0
MMIIC Data Transmit
MMTD7
0
MMTD6
MMTD5
MMTD4
MMTD3
MMTD2
MMTD1
MMTD0
Register Write:
(MMDTR)
Reset:
0
0
0
0
0
0
0
Read: MMRD7
MMRD6
MMRD5
MMRD4
MMRD3
MMRD2
MMRD1
MMRD0
MMIIC Data Receive
Register Write:
(MDDRR)
Reset:
0
0
0
0
0
0
0
0
Read: MMCRCD7 MMCRCD6 MMCRCD5 MMCRCD4 MMCRCD3 MMCRCD2 MMCRCD1 MMCRCD0
Write:
MMIIC CRC Data Register
(MMCRDR)
Reset:
Read:
0
0
0
0
0
0
0
0
0
0
0
MMBR2
1
0
MMBR1
0
0
MMBR0
0
MMIIC Frequency Divider
Register Write:
(MMFDR)
Reset:
0
0
0
0
0
= Unimplemented
Figure 14-1. MMIIC I/O Register Summary
14.4 Multi-Master IIC System Configuration
The multi-master IIC system uses a serial data line SDA and a serial clock line SCL for data transfer. All
devices connected to it must have open collector (drain) outputs and the logical-AND function is
performed on both lines by two pull-up resistors.
MC68HC908AP Family Data Sheet, Rev. 4
230
Freescale Semiconductor
FREESCALE [ Freescale ]
