Rainbow-electronics AT89C5122 Manual de usuario descargar pdf (Pagina 183)

183

AT8xC5122/23

4202E–SCR–06/06

Figure 110. Example of a Suspend/Resume Management

Smart Card Interface

Entering in Power-down Mode In order to reduce the power consumption, a power-down or idle mode can be invoked

by software (see Table 13, PCON register). Before activating these modes the applica-

tion will need to:

Power-off the Smart Card Interface by applying the following sequence:

• Set CRST pin at low level by clearing the bit CARDRST in SCCON register.

• Set CCLK pin at low level by clearing the bit CLK then the CARDCLK in SCCON

• Set CIO pin at low level by clearing the bit UART in SCICR register then the bit

CARDIO in SCCON register.

• Power the Smart Interface off by clearing the CARDVCC bit in SCCON register. This

instruction enables to switch DC/DC converter off.

CPRES input:

• Set the bit PRSEN in ISEL register

• Set the bit EX1 in IE0 register

• Set the bit EA in the IE0 register

• Invert the bit CPLEV in ISEL register (INT1 interrupt vector)

• Clear the bit PRESIT in the ISEL register

Exiting from Power-down

Mode

The microcontroller will exit from Power-down or Idle modes upon a reset or INT1 inter-

rupt which is a multiplexing of the interruptions generated by the CPRES pin (Card

detection), RxD flag (UART reception) and INT1 pin.

USB Controller Init

etection of a SUSPEND State

SPINT

Set SUSPCLK

Disable PLL

microcontroller in power-down

Detection of a RESUME State

WUPCPU

Enable PLL

Clear SUSPCLK

Clear WUPCPU bit

Clear SPINT

Note :

WUPCPU bit must be

Cleared before enabling

the PLL

Put the USB pads

in power down mod

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