HT46R006 datasheet(40/72 Pages) HOLTEK

40 / 72 page

HT48R006/HT46R006

Rev. 1.00

October 24, 2011

Prescaler

Bits TnPSC0~TnPSC2 of the TMRnC register can be

used to define a division ratio for the internal clock

source of the Timer/Event Counter enabling longer time

out periods to be setup.

Buzzer Function -- HT48R006

Operating similar to a programmable frequency divider,

the buzzer function within the microcontroller provides a

means of producing a variable frequency output suitable

for applications, such as piezo-buzzer driving or other

interfaces requiring a precise frequency generator.

BZ and BZ pins are a complimentary pair and

pin-shared with I/O pins, PA0 and PA1. The function is

selected via the CTRL0 register, however, if not se-

lected, the pins can operate as normal I/O pins. Note

that the BZ pin is the inverse of the BZ pin generating a

kind of differential output and supplying more power o

connected interfaces such as buzzers. The CTRL0 reg-

ister can select a single BZ pin or the complimentary pair

BZ and BZ. The accompanying table illustrates the truth

table of PA0/BZ and PA1/BZ.

The timer overflow signal is the clock source for the

buzzer circuit. The output frequency is controlled by

loading the required values into the timer prescaler and

timer registers to give the required division ratio. The

counter will begin to count-up from this preload register

value until full, at which point an overflow signal is gen-

erated, causing both the BZ and BZ outputs to change

state. The counter will then be automatically reloaded

with the preload register value and continue count-

ing-up.

If the CTRL0 register has selected the buzzer function,

then for both buzzer outputs to operate, it is essential

that the Port A control register PAC bit 0 and PAC bit 1

are setup as outputs. If only one pin is setup as an out-

put, the other pin can still be used as a normal data input

pin. However, if both pins are setup as inputs then the

buzzer will not function. The buzzer outputs will only be

activated if bit PA0 is set to

²1². This output data bit is

used as the on/off control bit for the buzzer outputs.

BZEN1

BZEN0

PAC Register

PAC0

PAC Register

PAC1

PA Data Register

PA0

PA Data Register

PA1

Output Function

PA0=BZ, PA1=BZ

PA0=0, PA1=0

PA0=BZ, PA1=input

PA0=0, PA1=input

PA0=input, PA1=D

PA0=input, PA1=input

Note:

The BZEN1 and BZEN0 bits are located in the CTRL0 register;

²I² stands for input

²O² stands for output

²x² stands for don¢t care

²D² stands for Data ²0² or ²1²

²C² CMOS output structure.

PA0/PA1 I/O Function Control

T i m e r O v e r f l o w

B u z z e r C l o c k

P A 0 D a t a

B Z O u t p u t a t P A 0

B Z O u t p u t a t P A 1

Buzzer Function

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