UPD784020 Datasheet, PDF (47/90 Pages) NEC – 16/8-BIT SINGLE-CHIP MICROCOMPUTER

mPD784020, 784021
9.5 EXAMPLES OF MACRO SERVICE APPLICATIONS
(1) Serial interface transmission
Transmission data storage buffer (memory)
Data n
Data n-1
Data 2
Data 1
Internal bus
TxD
Transmission
shift register
TXS (SFR)
Transmission control
INTST
Each time a macro service request (INTST) is generated, the next transmission data is transferred from memory
to TXS. When data n (last byte) has been transferred to TXS (that is, once the transmission data storage buffer
becomes empty), a vectored interrupt request (INTST) is generated.
(2) Serial interface reception
Reception data storage buffer (memory)
Data n
Data n-1
Data 2
Data 1
Internal bus
Reception buffer RXB (SFR)
RxD
Reception
shift register
Reception control
INTSR
Each time a macro service request (INTSR) is generated, reception data is transferred from RXB to memory.
When data n (last byte) has been transferred to memory (that is, once the reception data storage buffer becomes
full), a vectored interrupt request (INTSR) is generated.
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