NEC mPD789026 Subseries User Manual page 95

(1) 16-bit compare register 20 (CR20)
This register compares the value set to CR20 with the count value of 16-bit timer counter 20 (TM20), and
when they match, generates an interrupt request (INTTM2).
CR20 is set with a 16-bit memory manipulation instruction. The 0000H to FFFFH values can be set.
RESET input sets this register to FFFFH.
Cautions 1. This register is manipulated with a 16-bit memory manipulation instruction, however
an 8-bit memory manipulation instruction can be used. When manipulated with an 8-
bit memory manipulation instruction, accessing method should be direct addressing.
This register can be accessed only in short direct addressing mode when a 16-bit
memory manipulation instruction is used.
2. When rewriting CR20 during count operation, set CR20 to interrupt disable from
interrupt mask flag register 0 (MK0) beforehand. Beside, set the timer output data to
inversion disable by 16-bit timer mode control register 20 (TMC20).
If CR20 is rewritten with the interrupt enabled, an interrupt request may be issued
immediately.
(2) 16-bit timer counter 20 (TM20)
This is a 16-bit register that counts count pulses.
TM20 is read with a 16-bit memory manipulation instruction.
This register is in free running during count clock input.
RESET input clears this register to 0000H and after that to be in free running.
Cautions 1. The count value after releasing stop becomes undefined because the count operation
is executed during the oscillation settling time.
2. This register is manipulated with a 16-bit memory manipulation instruction, however
an 8-bit memory manipulation instruction can be used. When manipulated with an 8-
bit memory manipulation instruction, accessing method should be direct addressing.
This register can be accessed only in short direct addressing mode when a 16-bit
memory manipulation instruction is used.
3. When manipulated with an 8-bit memory manipulation instruction, readout should be
performed in the order from low-order byte to high-order byte and must be in pairs.
(3) 16-bit capture register 20 (TCP20)
This is a 16-bit register that captures the contents of 16-bit timer counter 20 (TM20).
TCP20 is set with a 16-bit memory manipulation instruction.
RESET input makes this register undefined.
Caution This register is manipulated with a 16-bit memory manipulation instruction, however an 8-
bit memory manipulation instruction can be used.
memory manipulation instruction, accessing method should be direct addressing. This
register can be accessed only in short direct addressing mode when a 16-bit memory
manipulation instruction is used.
(4) 16-bit counter read buffer
This buffer latches a counter value and retains a count value of 16-bit timer counter 20 (TM20).
CHAPTER 6 16-BIT TIMER
User's Manual U11919EJ3V0UM00
When manipulated with an 8-bit
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