HT66F13 datasheet(115/173 Pages) HOLTEK

115 / 173 page

Summary of A/D Conversion Steps

The following summarises the individual steps that should be executed in order to implement an A/D

conversion process.

· Step 1

Select the required A/D conversion clock by correctly programming bits ADCK2~ADCK0 in the

ADCR1 register.

· Step 2

Enable the A/D by clearing the ADOFF bit in the ADCR0 register to zero.

· Step 3

Select which channel is to be connected to the internal A/D converter by correctly programming the

ACS4 and ACS1~ACS0 bits which are also contained in the ADCR1 and ADCR0 registers.

· Step 4

Select which pins are to be used as A/D inputs and configure them by correctly programming the

ACE11~ACE0 bits in the ACERH and ACERL registers.

· Step 5

If the interrupts are to be used, the interrupt control registers must be correctly configured to ensure

the A/D converter interrupt function is active. The master interrupt control bit, EMI, and the A/D

converter interrupt bit, ADE, must both be set to high to do this.

· Step 6

The analog to digital conversion process can now be initialised by setting the START bit in the

ADCR0 register from low to high and then to low again. Note that this bit should have been

originally cleared to 0.

· Step 7

To check when the analog to digital conversion process is complete, the EOCB bit in the ADCR0

the A/D data registers ADRL and ADRH can be read to obtain the conversion value. As an

alternative method if the interrupts are enabled and the stack is not full, the program can wait for an

A/D interrupt to occur.

Note: When checking for the end of the conversion process, if the method of polling the EOCB bit in

the ADCR register is used, the interrupt enable step above can be omitted.

Rev. 1.10

115

February 9, 2011

HT66F13/HT66F14/HT66F15

Enhanced A/D Flash Type MCU

HT66F13 Datasheet(PDF) 115 Page - Holtek Semiconductor Inc