RPD functionality

AN2691

4/10

1.2

Power down

To reduce power consumption, the microcontroller can be switched to Power Down mode.

Clocking of all internal blocks is stopped, the contents of the internal RAM, however, are

The ST10 provides two different operating Power Down modes:

●

Protected Power Down mode

●

Interruptible Power Down mode

The Power Down operating mode is selected by the bit PWDCFG in the SYSCON register.

In the first case, the Power Down mode can only be entered if the NMI (Non Maskable

Interrupt) pin is externally pulled low while the PWRDN instruction is executed and the only

way to exit the Power Down mode is with an external hardware reset.

In the second case, the Power Down mode can be entered if enabled Fast External Interrupt

pins (EXxIN pins, alternate functions of Port 2 pins, with x = 7...0) are at their inactive level.

This inactive level is configured with the EXIxES bit field in the EXICON register, as follows:

Interruptible Power Down mode can be exited by asserting either RSTIN or one of the

enabled EXxIN pins (Fast External Interrupt).

EXICON (F1C0H / E0H)

ESFR

Reset value: 0000H

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

EXI7ES

EXI6ES

EXI5ES

EXI4ES

EXI3ES

EXI2ES

EXI1ES

EXI0ES

RW

RW

RW

RW

RW

RW

RW

RW

EXIxES

(x=7...0)

External Interrupt x Edge Selection Field (x=7...0)

‘00’: Fast external interrupts disabled: Standard mode.

EXxIN pin not taken into account for entering/exiting Power Down mode.

‘01’: Interrupt on positive edge (rising).

Enter Power Down mode if EXiIN = ‘0’, exit if EXxIN = ‘1’ (referred to as ‘high’ active level)

‘10’: Interrupt on negative edge (falling).

Enter Power Down mode if EXiIN = ‘1’, exit if EXxIN = ‘0’ (referred to as ‘low’ active level)

‘11’: Interrupt on any edge (rising or falling).

Always enter Power Down mode, exit if EXxIN level changed.