HT37B90 datasheet(56/80 Pages) HOLTEK

56 / 80 page

HT37B90/HT37B70/HT37B50/HT37B30

Rev.1.00

June22,2017

t A D C

A / D c o n v e r s i o n t i m e

t A D C

A / D c o n v e r s i o n t i m e

t A D C

A / D c o n v e r s i o n t i m e

0 0 0 B

0 1 0 B

S T A R T

E O C B

P C R 2 ~

P C R 0

A C S 2 ~

A C S 0

P o w e r - o n

R e s e t

E n d o f A / D

c o n v e r s i o n

1 : D e f i n e P B c o n f i g u r a t i o n

2 : S e l e c t a n a l o g c h a n n e l

S t a r t o f A / D

c o n v e r s i o n

R e s e t A / D

c o n v e r t e r

A / D s a m p l i n g t i m e

3 2 t A D

0 1 1 B

0 0 0 B

S t a r t o f A / D

c o n v e r s i o n

R e s e t A / D

c o n v e r t e r

0 0 0 B

1 . P B p o r t s e t u p a s I / O s

2 . A / D c o n v e r t e r i s p o w e r e d o f f

t o r e d u c e p o w e r c o n s u m p t i o n

1 0 0 B

0 0 1 B

S t a r t o f A / D

c o n v e r s i o n

R e s e t A / D

c o n v e r t e r

D o n 't c a r e

E n d o f A / D

c o n v e r s i o n

E n d o f A / D

c o n v e r s i o n

S T A R T b i t s e t h i g h w i t h i n o n e t o t e n i n s t r u c t i o n c y c l e s a f t e r t h e P C R 0 ~ P C R 2 b i t s c h a n g e s t a t e

A / D s a m p l i n g t i m e

3 2 t A D

A / D s a m p l i n g t i m e

3 2 t A D

A/DConversionTiming

SummaryofA/DConversionSteps

The following summarizes the individual steps that

should be executed in order to implement an A/D con-

versionprocess.

· Step1

Select the required A/D conversion clock by correctly

programming bits ADCS1 and ADCS0 in the ACSR

· Step2

Select which channel is to be connected to the internal

A/D converter by correctly programming the

ACS2~ACS0 bits which are also contained in the

ADCR register.

· Step3

Select which pins on Port B are to be used as A/D in-

puts and configure them as A/D input pins by correctly

programming the PCR2~PCR0 bits in the ADCR reg-

ister. Note that this step can be combined with Step 2

into ADCR registersprogrammingoperation.

· Step4

The analog to digital conversion process can now be

initialised by setting the START bit in the ADCR regis-

ter from

²0² to ²1² and then to ²0² again. Note that this

bitshouldhavebeenoriginallysetto

²0².

· Step5

To check when the analog to digital conversion pro-

cess is complete, the EOCB bit in the ADCR register

can be polled. The conversion process is complete

when this bit goes low. When this occurs the A/D data

registers ADRL and ADRH can be read to obtain the

conversionvalue.

The following timing diagram shows graphically the vari-

ous stages involved in an analog to digital conversion

processanditsassociatedtiming.

HT37B90 Datasheet(PDF) 56 Page - Holtek Semiconductor Inc

HT37B90 Datasheet(HTML) 56 Page - Holtek Semiconductor Inc

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