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CHAPTER 12 DTP/external interrupt
12.4.2
DTP Function
The DTP/external interrupt has the DTP function that detects the signal from an external
peripheral device through the DTP/external interrupt pin or RX pin to start Extended
Intelligent I/O Service (EI
I DTP Function
The DTP function detects the signal level set by the detection level setting register of the DTP/external
interrupt function to start the EI
• When the EI
accepted by the CPU, the DTP function starts the EI
• Upon completion of transfer of one data item, the descriptor is updated and the DTP/external interrupt
request flag bit is cleared to prepare for the next request from the DTP/external interrupt pin and RX
pin.
• When the EI
Figure 12.4-3 Example of Interface with External Peripheral Device
Input to INT4 pin
(DTP factor)
CPU internal
operation
Peripheral
equipment
of external
connection
Data
transmisson
request
1 This must be cancelled within three machine clooks after the start of data transfer.
2 When EI
342
2
OS).
2
OS.
2
OS operation is already enabled (ICR: ISE = 1) at the point when the interrupt request is
2
OS completes transfer of all the data, control branches to the interrupt processing.
"H" level request (ELVR LB4 LA4=01
Descriptor
select and read
1
DTP factor
INT
2
OS in "peripheral function
2
OS and starts data transfer.
)
B
Internal data bus
DTP/extenal
Interrupt
CPU
interrupt
request
EI
circuit
internal memory transfer".
Descriptor
renewal
Read/Write
2
operation
Internal
2
OS
memory
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