ADE75 datasheet(71/148 Pages) AD

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Preliminary Technical Data

ADE75xx/ADE71xx

Rev. PrE | Page 71 of 148

initiated by setting the TADC bit in the Start ADC

Measurement SFR (ADCGO, 0xD8). Background temperature

measurements are not available.

PSM2: In this operating mode, the 8052 is not active.

Temperature conversions are available through the background

measurement mode only.

The Temperature ADC value SFR (TEMPADC, 0xD7) is

updated with a new value only when a temperature ADC

interrupt occurs.

Temperature ADC interrupt

The temperature ADC can generate an ADC interrupt when at

least one of the following conditions occurs:

- The difference between the new temperature ADC value and

the last temperature ADC value generating an ADC interrupt is

larger than the value set in the TEMP_DIFF bits.

- The Temperature ADC conversion, initiated by setting TADC

in the Start ADC Measurement SFR (ADCGO, 0xD8), is

finished.

When the ADC interrupt occurs, a new value is available in the

Temperature ADC value SFR (TEMPADC, 0xD7). Note that

there is no flag associated with this interrupt.

BATTERY MEASUREMENT

To provide a digital battery measurement, the

ADE75XX/ADE71XX includes a dedicated ADC. The battery

measurement is available in an 8-bit SFR (Battery ADC value

SFR (BATADC, 0xDF). The battery measurement has a

resolution of 15 mV/LSB. A battery conversion can be initiated

by two methods:

- Single Battery Measurement

- Background Battery Measurements

Single Battery Measurement

Set the BTADC bit in the Start ADC Measurement SFR

(ADCGO, 0xD8) to get a battery measurement. An interrupt

will be generated when the conversion is done and the battery

measurement is available in the Battery ADC value SFR

(BATADC, 0xDF).

Background Battery measurements

To configure background measurements for the battery,

establish a measurement interval in the Peripheral ADC Strobe

Period SFR (STRBPER, 0xF9). Then battery measurements will

be performed periodically in the background – see Table 46.

When a battery conversion completes, the battery ADC value is

compared to the low battery threshold, established in the

Battery detection threshold SFR (BATVTH, 0xFA). If it is below

this threshold, a low battery flag is set. This low battery flag is

the BATTFLAG bit in the Power Management Interrupt Flag

SFR (IPSMF, 0xF8), used for power supply monitoring. This low

battery flag can be enabled to generate the PSM interrupt by

setting the EBATT bit in the Power Management Interrupt

Enable SFR (IPSME, 0xEC). This method allows battery

measurements to take place completely in the background, only

requiring MCU activity if the battery drops below a user

specified threshold.

To set up background battery measurements:

Configure the Battery detection threshold SFR

(BATVTH, 0xFA) to establish a low battery threshold.

If the BATADC measurement is below this threshold,

the BATTFLAG in the Power Management Interrupt

Flag SFR (IPSMF, 0xF8) will be set.

Set up the interval for background battery

measurements by configuring the

BATT_PERIOD[1:0] bits.

Battery ADC in PSM1 and PSM2

Depending on the operating mode, a battery conversion is

initiated only by certain actions:

PSM0: In this operating mode, the 8052 is active. Battery

measurements are available in the background measurement

mode and by initiating a single measurement.

PSM1: In this operating mode, the 8052 is active and the part is

powered from battery. Single battery measurements can be

initiated by setting the BTADC bit in the Start ADC

Measurement SFR (ADCGO, 0xD8). Background battery

measurements are not available.

PSM2: In this operating mode, the 8052 is not active. Battery

conversions are available through the background measurement

mode only.

Battery ADC interrupt

The battery ADC can generate an ADC interrupt when at least

one of the following conditions occurs:

- The new battery ADC value is smaller than the value set in the

Battery detection threshold SFR (BATVTH, 0xFA), indicating a

battery voltage loss.

- A single battery measurement, initiated by setting the

BATT_ADC_GO bit, is finished.

When the battery flag is set in the Power Management Interrupt

Flag SFR (IPSMF, 0xF8), a new ADC value is available in the

Battery ADC value SFR (BATADC, 0xDF). This battery flag can

be enabled as a source of the PSM interrupt to generate a PSM

interrupt every time the battery drops below a set voltage

threshold or after a single conversion initiated by setting the

BATT_ADC_GO bit is ready.

The Battery ADC value SFR (BATADC, 0xDF) is updated with a

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