AN3269

Application description

Doc ID 17904 Rev 1

7/19

converts the resulting voltage, image of the consumption current.

In low power modes only, a counter enabled by STM8L (PC4 pin) manages the

measurement timing while the microcontroller is idle. The microcontroller is woken-up after a

150 ms delay controlled by the K2 switch.

While the microcontroller is in one of the power saving modes, a capacitor (C) is able to

store the measurement charge so that the microcontroller can later give the value of Low

power mode current consumption early on in the microcontroller wake-up phase (in the first

50 ms). Switch S is opened at device start-up in order to keep the charge collected in

capacitor (C) intact while the microcontroller is in low power mode.

The current measurement precision is enhanced by taking into account the I bias current of

circuitry disabled), a special test invoked by the user at device start-up measures this

current value and stores it in the non-volatile memory. Once this value is stored in the

current (see Section 1.5.2: Bias current record).

DISCOVERY evaluation board user manual (UM0970).

1.5

Getting started with the application

This STM8L-DISCOVERY example application has 3 application modes that can be run:

●

●

Bias current record

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Manufacturing test

Demo mode is available at application power-up while the two other ones are called by the

user according to a specific procedure that is detailed later in this chapter. However, for best

performance, it is recommended to control and record the Bias current before starting

1.5.1

Once the application is powered-up via the USB cable (or by external power supply), it starts

voltage applied to the STM8L device.

are displayed, both LEDs are turned off.

The User push-button allow you to change the functions as described in the state diagram in

Figure 3. Each function consists of configuring the device with any required settings and

then measuring and displaying the result on the LCD panel.