NEC UPD703116 User Manual page 316

32-bit single-chip microcontrollers

Table of Contents

(2) Operation in UDC mode

(a) Overview of operation in UDC mode

The count clock input to TM1n in the UDC mode (CMD bit of TUMn register = 1) can only be external

input from the TIUD1n and TCUD1n pins. Up/down count judgment in the UDC mode is determined

based on the phase difference of the TIUD1n and TCUD1n pin inputs according to the PRM1n register

setting (there is a total of four choices).

PRM1n Register

The UDC mode is further divided into two modes according to the TM1n clear conditions (count operation

is performed only with TIUD1n, TCUD1n input in both modes).

• UDC mode A (TUMn register's CMD bit = 1, MSEL bit = 0)

The TM1n clear source can be selected as only external clear input (TCLR1n), a match signal

between the TM1n count value and the CM1n0 set value during up-count operation, or logical sum

(OR) of the two signals, using bits CLR1 and CLR0 of the TMC1n register.

TM1n can transfer the value of CM1n0 upon occurrence of TM1n underflow.

• UDC mode B (TUMn register's CMD bit = 1, MSEL bit = 1)

The status of TM1n after match of the TM1n count value and CM1n0 set value is as follows.

<1> In the case of up-count operation, TM1n is cleared (0000H), and the INTCM1n0 interrupt is

<2> In the case of down-count operation, the TM1n count value is decremented (−1).

The status of TM1n after match of the TM1n count value and CM1n1 set value is as follows.

<1> In the case of up-count operation, the TM1n count value is incremented (+1).

<2> In the case of down-count operation, TM1n is cleared (0000H), and the INTCM1n1 interrupt is

CHAPTER 9 TIMER/COUNTER FUNCTION

Table 9-7. List of Count Operations in UDC Mode

Down count when TCUD1n = high level

Up count when TCUD1n = low level

Up count upon detection of valid edge of TIUD1n input

Down count upon detection of valid edge of TCUD1n input

Up count upon detection of valid edge of TIUD1n input when

TCUD1n = high level

Down count upon detection of valid edge of TIUD1n input

when TCUD1n = low level

Automatic judgment upon detection of both edges of TIUD1n

input and both edges of TCUD1n input

User's Manual U14492EJ5V0UD

TM1n Operation