Notes On Dtp/External Interrupt Unit Usage - Fujitsu F2MC-16LX Hardware Manual

18.4 Notes on DTP/External Interrupt Unit Usage

This section provides notes on using the DTP/external interrupt unit.
I Conditions for external connection of peripheral devices
For support by the DTP unit, external peripheral devices must be able to automatically clear a
request after successful data transfer. If a transfer request fails to be withdrawn within three
machine cycles after the transfer operation starts (interim value), the DTP unit will proceed as if
a new transfer request had been generated.
I Procedure for DTP/external interrupt unit operation
Set the values of registers in the DTP/external interrupt unit as follows:
(1) Set the bits for the registers to be enabled to "disable".
(2) Set the bits of the request level setting register.
(3) Clear the bits in the source register.
(4) Set the bits for the registers to be enabled to "enable".
Steps (3) and (4) allow simultaneous writing by word-length specification.
To set the contents of DTP/external interrupt unit registers, first disable the registers to be
enabled. Before enabling the registers to be enabled again, clear the source register in order to
avoid accidental generation of an interrupt source in register set mode or interrupt enabled
mode.
CHAPTER 18 DTP/EXTERNAL INTERRUPT UNIT
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