AS8218 datasheet(26/123 Pages) AMSCO

26 / 123 page

Data Sheet AS8218 / AS8228

Revision 3.0, 31-May-06

Page 26 of 123

has been taken. If the ‘ack’ bit is not reset the P_ACCU will add the ‘old’ energy information to the ‘new’ energy

information accumulated in the following cycle.

In any event, the MCU must reset the dai flag in order to clear the interrupt.

Wait for

fast pulse

Increment

P_ACCU

np = 0

New fast

pulse?

np = P_ACCU + np (old)

P_ACCU = 0

nsamp

reached?

IE.0 = 1

dai = 1

ack = 1

ack = 0?

Note: The above flow chart assumes that the dai flag is always reset in time before the next interrupt is

generated.

Pulse Generation

Two pulse generators are provided to ensure that virtually any LED pulse rate output can be programmed for

display and calibration purposes. The first pulse generator (Fast Pulse Gen) produces fast internal pulses.

These fast pulses are accumulated in the power accumulator (P_ACCU) for energy data transfer to the MCU.

The second pulse generator (LED Pulse Gen) produces the LED output pulses (meter constant) from the fast

internal pulses. This type of data interface ensures that the MCU receives exactly the same energy information

as is displayed by the LED pulses.

In case of ‘creep’, the power samples to be added will be set to 0. This has the advantage that previously

recorded energy is not lost and remains exactly the same.

The following flow chart shows the basic flow diagram for pulse generation:

AS8218 Datasheet(PDF) 26 Page - ams AG