enable the counter from the first FIN rising edge to the next rising edge, then will generate an interrupt. It may

also use FREQ (internal frequency generator output) as clock input, hence counting the CX interval. For

measuring the resistor value of the temperature and humidity sensor, we must first measure the frequency of

Rref, then the frequency of Sensor:

Fref= K / Rref CX and

Fsensor= K / Rsensor CX, hence

Rsensor = Rref * Freq / Fsensor.

The CX input can be used as a clock counter.

Analog-to-Digital converter

The diagram is shown below:

LHCP

ENCP

ADF1

ADF2

ADF3

ADF4

AN1

AN2

AN3

2

1

Analog Switch

2

1

Analog Switch

LBR

Low Battery

Reference

4-Bit Ladder

DAC

ENLBR

ENDAC

MDA

DAC

AN4

0 123

MPW1

MPW2

6 / 8-Bit

PWM DAC

01 2 3 4 567

6 / 8-Bit

PWM DAC

01 2 3 4 567

MPW1

MPW2

The use of these blocks is illustrated below:

Comparator: Sets negative input as AN4, compare with AN1, 2, 3.

4-bit ADC: Sets negative input as internal 4-bit DAC, positive input as AN4, software control for AN1, 2, 3,

4 analog value archive.

Low battery detector: Sets negative input as internal 4-bit DAC, positive input as LBR (low battery

reference). If the DAC level is lower than LBR, it means there is a low-battery condition.

PWM DAC output: With an external RC network, 6-bit or 8-bit PWM DAC can be used.

6-bit/ 8-bit ADC: Sets negative input as AN4, connects from PWM with an external RC network. You can

get analog value from AN1, 2, 3.

Supply voltage measurement: Sets negative input as AN4, connects from PWM with an external RC

network, positive input is LBR. If comparative data is N, the supply voltage is LBR (about 1.26V) * 255 / N.

PWM is 0/63, 1/63, 62/63 and 63/63, and the level of 8-bit PWM is 0/255, 1/255, 254/255 and 255/255.

Preliminary

10

Ver. 0.0

APU428