M37280MF Datasheet, PDF (44/178 Pages) Mitsubishi Electric Semiconductor – SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER with CLOSED CAPTION DECODER and ON-SCREEN DISPLAY CONTROLLER

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MITSUBISHI MICROCOMPUTERS
M37280MF–XXXSP, M37280MK–XXXSP
M37280EKSP
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER with CLOSED CAPTION DECODER
and ON-SCREEN DISPLAY CONTROLLER
S Slave address R/W A Data A Data A/A P
7 bits
“0”
1 to 8 bits
1 to 8 bits
(1) A master-transmitter transmits data to a slave-receiver
S Slave address R/W A Data A Data A P
7 bits
“1”
1 to 8 bits
1 to 8 bits
(2) A master-receiver receives data from a slave-transmitter
S
Slave address
1st 7 bits
R/W
A
Slave address
2nd byte
A
Data
A Data A/A P
7 bits
“0”
8 bits
1 to 8 bits
1 to 8 bits
(3) A master-transmitter transmits data to a slave-receiver with a 10-bit address
S
Slave address
1st 7 bits
R/W
A
Slave address
2nd byte
A
Sr
Slave address
1st 7 bits
R/W
Data
A
Data
A
P
7 bits
“0”
8 bits
7 bits
“1” 1 to 8 bits
(4) A master-receiver receives data from a slave-transmitter with a 10-bit address
1 to 8 bits
S : START condition
A : ACK bit
Sr : Restart condition
P : STOP condition
R/W : Read/Write bit
From master to slave
From slave to master
Fig. 12.6.12 Address Data Communication Format
12.6.12 Precautions when using multi-master I²C-BUS interface
(1) Read-modify-write instruction
The precautions when the raead-modify-write instruction such as SEB,
CLB etc. is executed for each register of the multi-master I²C-BUS
interface are described below.
•I²C data shift register (S0)
When executing the read-modify-write instruction for this register
during transfer, data may become a value not intended.
•I²C address register (S0D)
When the read-modify-write instruction is executed for this register
at detecting the STOP condition, data may become a value not
______
intended. It is because hardware changes the read/write bit (RBW)
at the above timing.
•I²C status register (S1)
Do not execute the read-modify-write instruction for this register
because all bits of this register are changed by hardware.
•I²C control register (S1D)
When the read-modify-write instruction is executed for this register
at detecting the START condition or at completing the byte transfer,
data may become a value not intended. Because hardware changes
the bit counter (BC0–BC2) at the above timing.
•I²C clock control register (S2)
The read-modify-write instruction can be executed for this register.
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(2) START condition generating procedure using multi-master
ŒProcedure example (The necessary conditions of the generating
procedure are described as the following  to ).
•
•
LDA —
SEI
BBS 5,S1,BUSBUSY
BUSFREE:
STA S0
LDM #$F0, S1
CLI
•
•
BUSBUSY:
CLI
•
•
(Taking out of slave address value)
(Interrupt disabled)
(BB flag confirming and branch process)
(Writing of slave address value)
(Trigger of START condition generating)
(Interrupt enabled)
(Interrupt enabled)
Use “STA,” “STX” or “STY” of the zero page addressing instruction
for writing the slave address value to the I²C data shift register.
ŽUse “LDM” instruction for setting trigger of START condition gener-
ating.
Write the slave address value of above  and set trigger of START
condition generating of above Ž continuously shown the above
procedure example.
Disable interrupts during the following three process steps:
• BB flag confirming
• Writing of slave address value
• Trigger of START condition generating
When the condition of the BB flag is bus busy, enable interrupts
immediately.
Rev. 1.0