STPM01 datasheet(30/60 Pages) STMICROELECTRONICS

30 / 60 page

Theory of operation

STPM01

30/60

Doc ID 10853 Rev 8

When a no-load condition is detected MOP and MON are held low.

8.16

Using STPM01 in microcontroller based meter (peripheral)

The higher flexibility of STPM01 allows its use in very high end microcontroller based energy

meters. In this case the STPM01 must be programmed to work in peripheral mode, all the

SPI pins (SCS, SCLNCL, SDATD, SYN) are used only for communication purposes allowing

the microcontroller to write and read the internal STPM01 registers. The peripheral mode

has two further different configuration modes according to the status of the APL

configuration bit. The APL bit status changes the function of MOP, MON and LED pins

according to the description below.

APL = 0:

In the MOP pin, the ZCR signal is available (see paragraph 3 for details about ZCR signal);

The pin MON provides the DOG signal. The DOG signal generates a 16 ms long positive

pulse every 1.6 seconds. Generation of these pulses can be suspended if data are read in

intervals shorter than 1.6 s. The DOG signal is actually a watchdog reset signal which can

be used to control an operation of an on-board microcontroller. It is set to high whenever the

VDDA voltage is below 2.5 V, but after VDDA goes above 2.5 V this signal starts to run.

Figure 21.

Positive energy stepper driving signals

MON

MOP

Figure 22.

Negative energy stepper driving signals

MON

MOP

STPM01 Datasheet(PDF) 30 Page - STMicroelectronics