AS8267 datasheet(33/136 Pages) AMSCO

33 / 136 page

Data Sheet AS8267 / AS8268

Revision 1.0, 19-Jun-07

Page 33 of 136

LED Output Timing

The pulses on the LED output indicate the amount of energy that has been consumed over a certain period of

time. Each pulse has an equivalent that can be set in the SREG/mconst register exactly. The unit is impulses

per kWh (i/kWh).

This output may be used for calibration.

The polarity of the LED pulses may be selected via the ledpol bit in the SREG/Select Register for either

positive or negative going pulses.

Timing Diagram

Timing Parameters

Parameter

Symbol

Min

Typ

Max

Unit

Notes

Pulse width

50% duty cycle is enabled when the LED

period is less than 160ms. For mconst=0,

t1 will be 17.9µs.

One register block contains the data for the Meter Data Register (MDR) and the Settings Register (SREG),

hence only one interface to the MCU is required.

Meter Data Register (MDR)

The meter data register is updated after ‘nsamp’ samples. Then an interrupt is issued to the MCU, which may

take the energy data and process them further on. When an interrupt is generated the ‘ack’ bit in the

SREG/Status register is set. If the MCU takes the data, it has to reset the ‘ack’ bit.

If the ‘ack’ bit has not been reset by the MCU when a new set of data is ready, the previous np value will be

added to the new one.

In any case the dai flag in the SREG/Status register must be reset in order to clear the interrupt.

AS8267 Datasheet(PDF) 33 Page - ams AG