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CHAPTER 18 METER CONTROLLER/DRIVER
(2) Compare register n0 (MCMPn0)
MCMPn0 is an 8-bit register that can rewrite compare values through specification of bit 4 (TENn) of the compare
control register n (MCMPCn).
RESET input sets this register to 00H and clears hardware to 0.
MCMPn0 is a register that supports read/write only for 8-bit access instructions. MCMPn0 continuously compares
its value with the MCNT value. When the above two values match, a match signal of the sin side of meter n is
generated.
(3) Compare register n1 (MCMPn1)
MCMPn1 is an 8-bit register that can rewrite compare values through specification of bit 4 (TENn) of the compare
control register n (MCMPCn).
RESET input sets this register to 00H and clears hardware to 0.
MCMPn1 is a register that supports read/write only for 8-bit access instructions. MCMPn1 continuously compares
its value with the MCNT value. When the above two values match, a match signal of the cos side of meter n is
generated.
(4) 1-bit addition circuit
The 1-bit addition circuit repeats 1-bit addition/non-addition to PWM output alternately upon MCNT overflow
output, and enables the state of PWM output between current compare value and the next compare value. This
circuit is controlled by bits 2 and 3 (ADBn0, ADBn1) of the MCMPCn register.
(5) Output control circuit
This circuit consists of a Pch and Nch drivers and can drive a meter in H bridge configuration by connecting a
coil. When a meter is driven in half bridge configuration, the unused pins can be used as normal output port
pins.
The relation of the duty factor of the PWM signal output from the SMnm pin is indicated by the following expression
(n = 1 to 4, m = 0, 1).
PWM (duty) =
Set value of MCMPnm
×
cycle of MCNT count clock
×
100%
255
×
cycle of MCNT count clock
=
Set value of MCMPnm
×
100%
255
Cautions 1. MCMPn0 and MCMPn1 cannot be read or written by a 16-bit access instruction.
2. MCMPn0 and MCMPn1 are in master-slave configuration, and MCNT is compared
with a slave register. The PWM pulse is not output until the first overflow occurs
after the counting operation has been started because the compare data is not
transferred to the slave.
Summary of Contents for mPD780973 Series
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