Hardware and layout

UM0970

16/30

Doc ID 17693 Rev 2

3.6.4

Ibias current measurement procedure

In Low power mode the bias current of operational amplifier input (U4 pin 4) is not negligible

measurement since this current is not sinked by the MCU. Ibias is measured during

production test and stored in the MCU EPROM. The demonstration software, Discover, uses

demonstration software and can be launched if required.

The procedure for Ibias measurement (implemented in the Demo) is:

1.

Power off the board (disconnect the USB cable).

2.

Set jumper JP1 to OFF position (pins 1 and 2).

3.

Push down B2 (USER button), power on the board from the USB.

4.

Wait at least 1 second before releasing B2, the LCD displays the Ibias measurement.

5.

Power off the board (disconnect the USB cable).

6.

Set jumper JP1 to ON position (pins 2 and 3). The Ibias value is now stored. The bias

3.7

Solder bridges

Table 4.

Solder bridge

Bridge

1.

Default state is in bold type.

Description

SB1,2

(X2 crystal)

Off

PA2, PA3 are disconnected from P1

X2, C19, C20 and R24 provide a clock as shown in schematics

On

PA2, PA3 are connected to P1 (X2, C19, C20, R24 must not be fitted)

SB3,5,7,9

(DEFAULT)

On

Reserved, do not modify

SB4,6,8,10

(PRG-32)

Off

Reserved, do not modify

SB11,12,14

(IDD_Measurement)

Off

PFO, PE6, PC4 are available and IDD module cannot be used

JP1 must be set to OFF

On

PFO, PE6, PC4 are used by IDD module

JP1 must be set to ON

SB13,15

(X3 crystal)

Off

PC5, PC6 are only connected to P2 (but do not remove X3, C21, C23, R27)

On

PC5, PC6 are connected to P2. X3, C21, C23 and R27 provide 32 KHz clock

SB16

(B1-RESET)

Off

PA1/RESET signal is only connected to P1

On

PA1/RESET signal is used by ST_LINK as SWIM_RST and also connected to P1

SB17

(B2-USER)

Off

PC1 is only connected to P2

On

PC1 is connected to P2 and push button B2 for user