EM78P342NP datasheet(63/102 Pages) EMC

63 / 102 page

EM78P341N/342N/343N

8-Bit Microprocessor with OTP ROM

Product Specification (V1.0) 12.01.2006

• 57

(This specification is subject to change without further notice)

6.7.5 ADC Operation during Sleep Mode

In order to obtain a more accurate ADC value and reduce power consumption, the AD

conversion remains operational during sleep mode. As the SLEP instruction is

executed, all the MCU operations will stop except for the Oscillator, TCC, TCCA,

TCCB, TCCC and AD conversion.

The AD Conversion is considered completed as determined by:

1. ADRUN bit of R9 register is cleared to “0”.

2. ADIF bit of RE register is set to “1”.

3. ADWE bit of the RE register is set to “1.” Wake-up from ADC conversion (where it

remains in operation during sleep mode).

4. Wake-up and executes the next instruction if ADIE bit of IOCE0 is enabled and the

“DISI” instruction is executed.

5. Wake-up and enters into Interrupt vector (Address 0x00C) if ADIE bit of IOCE0 is

enabled and the “ENI” instruction is executed.

6. Enters into Interrupt vector (Address 0x00C) if ADIE bit of IOCE0 is enabled and the

“ENI” instruction is executed.

The results are fed into the ADDATA, ADDATA1H, and ADDATA1L registers when the

conversion is completed. If the ADIE is enabled, the device will wake up. Otherwise,

the AD conversion will be shut off, no matter what the status of ADPD bit is.

6.7.6 Programming Process/Considerations

6.7.6.1 Programming Process

Follow these steps to obtain data from the ADC:

1. Write to the seven bits (ADE7:ADE0) on the R8 (AISR) register to define the

characteristics of R5 (digital I/O, analog channels, or voltage reference pin)

2. Write to the R9/ADCON register to configure the AD module:

a) Select the ADC input channel (ADIS2: ADIS0)

b) Define the AD conversion clock rate (CKR1: CKR0)

c) Select the VREFS input source of the ADC

d) Set the ADPD bit to 1 to begin sampling

3. Set the ADWE bit, if the wake-up function is employed

4. Set the ADIE bit, if the interrupt function is employed

5. Write “ENI” instruction, if the interrupt function is employed

6. Set the ADRUN bit to 1

7. Write “SLEP” instruction or Polling.

8. Wait for wake-up, ADRUN bit is cleared to “0”, interrupt flag (ADIF) is set “1,” or

ADC interrupt occurs.

EM78P342NP Datasheet(PDF) 63 Page - ELAN Microelectronics Corp