MC68HC11P2 Datasheet, PDF (111/268 Pages) Motorola, Inc – Microcontrollers

Freescale Semiconductor, Inc.
Motorola Interconnect Bus (MI BUS)
Push-pull sequence
6.3 Push-pull sequence
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.
Time slots
Push-pull function
Push (biphase coded)
Pull (NRZ coded)
TXD pin (true data)
MI BUS wire
Bit fields
10
01
01234567
Start
Stop
Start
Push
sync
D0
D1
D2
D3
D4
A0
A1
A2
Pull
sync
Data
Address
Push field
(driven by MCU)
Message frame
NRZ
Data
End of frame
Pull field
(driven by slave)
Figure 6-1. MI BUS timing
MC68HC11P2 — Rev 1.0
Motorola Interconnect Bus (MI BUS)
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Technical Data