UPD784938 Datasheet, PDF (480/733 Pages) NEC – 16-Bit Single-Chip Microcontrollers

CHAPTER 20 IEBus CONTROLLER
20.2 Simple IEBus Controller
The µPD784938 has a newly developed IEBus controller. The functions of this IEBus controller are limited as compared
with the IEBus interface functions of the existing models (provided to the 78K/0 Series).
Table 20-7 compares the IEBus interface functions of the existing models with the simple IEBus interface functions of
the µPD784938 Subseries.
Table 20-7. Comparison between Existing and Simple IEBus Interface Functions
Item
Communication mode
Internal system clock
Internal buffer size
CPU processing
Hardware processing
Existing Function (IEBus of 78K/0)
Simple IEBus
Modes 0, 1, and 2
Fixed to mode 1
6.0 (6.29) MHz
Transmit buffer: 33 bytes (FIFO)
Receive buffer: 40 bytes (FIFO)
Up to 4 frames can be received.
Transmit/receive data register
Communication start preprocessing (data setting)
Setting and management of each communication
status
Writing data to transmit buffer
Reading data from receive buffer
Communication start preprocessing (data setting)
Setting and management of each communication
status
1-byte data write processing
1-byte data read processing
Management of transmission such as slave status
Management of plural frames, master request
reprocessing
Bit processing (modulation/demodulation, error
detection)
Field processing (generation/management)
Arbitration result detection
Parity processing (generation/error detection)
Automatic return of ACK/NACK
Automatic data re-processing
Automatic master re-processing^Note
Transmission processing such as automatic slave
status transmission
Plural-frame reception processing
Bit processing (modulation/demodulation, error
detection)
Field processing (generation/management)
Arbitration result detection
Parity processing (generation/error detection)
Automatic return of ACK/NACK
Automatic data transmission re-processing
Note Automatic master re-processing: After generating the master request, if the master request is cancelled by
arbitration, etc., the bus is released and automatically re-issue the master
request.
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Preliminary User’s Manual U13987EJ1V0UM00