MC68HC912D60 Motorola, MC68HC912D60 Datasheet - Page 290

• Manufacturer Part Number: MC68HC912D60
• Description: Microcontrollers
• Manufacturer: Motorola

Motorola Interconnect Bus
16.3 Push-pull sequence
Technical Data
290
violates the rules of Manchester biphase encoding. Up to eight slave
devices may be addressed by the MI Bus. Other features of MI Bus
include message validation, error detection, and default value setting.
On the MC68HC912D60A the MI Bus module shares the same pins on
port S as the SCI0 module. Data is transmitted (or ‘pushed’) via the TxD0
pin, and received (‘pulled’) via the RxD0 pin. While data is being pushed,
RxD0 will be disconnected from the receiver circuitry. The message
frame is handled automatically in hardware. The MCU register interface
is similar to that for the SCI.
Communication between the MCU and the slave device always utilizes
the same frame organization. First, the MCU sends serial data to the
selected device. This data field is called the ‘push field’. At the end of the
push field, the selected device automatically sends back to the MCU the
data held during the push sequence. The MCU reads the serial data sent
by the selected device. This data is called the ‘pull field’ and contains
status information followed by the end-of-frame information from the
selected device.
Freescale Semiconductor, Inc.
TxD0 pin (true data)
Push-pull function
For More Information On This Product,
MI Bus wire
Time slots
Bit fields
Go to: www.freescale.com
Motorola Interconnect Bus
Start
Figure 16-1. MI Bus timing
Push
sync D0 D1 D2 D3 D4 A0 A1 A2
1 0
(driven by MCU)
Push (biphase coded)
Data
Push field
Message frame
Address
Start
sync
Pull
MC68HC912D60A — Rev 3.0
0 1
0
1
Data
NRZ
Pull (NRZ coded)
(driven by slave)
2 3 4
Pull field
End of frame
5
Stop
6 7
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