PC8374L datasheet(84/239 Pages) NSC

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4.0 System Wake-Up Control (SWC) (Continued)

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Keyboard Wake-Up Events

Keyboard wake-up events are also detected by the Keyboard/Mouse Wake-Up Detector, which monitors the KBCLK and

KBDAT signals. Since the detection mechanisms for keyboard and mouse events are independent, they can be operated

simultaneously. Moreover, the Keyboard signals may be swapped with the Mouse signals, by setting SWAP bit in KBC Con-

figuration register (see Section 3.13.3 on page 72). The Keyboard/Mouse Wake-Up Detector is powered by VSB3 and works

independently of the Keyboard Controller module (powered by VDD3).

The keyboard event detection mechanism can be programed to detect:

● Any keystroke (Fast Any-Key or Special Key Sequence modes).

● A speciﬁc programmable sequence of up to eight alphanumeric keystrokes (Password mode).

● Any programmable sequence of up to eight bytes of data received from the keyboard (Special Key Sequence mode).

● Up to three programmable Power Management keys concurrently available, each including a sequence of up to three

bytes of data received from the keyboard (Power Management Keys mode).

The Keyboard/Mouse Wake-Up Detector has four operation modes:

● Fast Any-Key mode

● Password mode

● Special Key Sequence mode

● Power Management Keys mode

Up to eight Keyboard Data registers (PS2KEY0-7) are used to define which keyboard data string generates an event. Since

the same set of registers is used by three of the four operation modes, only one mode can be selected at a time.

For modes involving more than one keystroke, the maximum delay allowed between pressing two consecutive keys is 4 sec-

onds. A longer delay is interpreted by the Wake-Up Detector as the beginning of a new sequence of keystrokes, which caus-

es the present sequence to be discarded. In all operation modes, pressing a wrong key requires a recovery time of 4

seconds, before a new (correct) sequence may be recognized.

Fast Any-Key Mode. In this mode, pressing any key on the keyboard is identified as a keyboard event and, as a result,

KBD_ANYK_STS bit in GPE1_STS_2 register is set (see Section 4.4.6 on page 102). The status bit is cleared only when

the software writes 1 to it. The key data contained in the PS2KEY0-7 registers is ignored. To program the Keyboard/Mouse

Wake-Up Detector to operate in Fast Any-Key mode, set KBDMODE ﬁeld in KBDWKCTL register to ‘01’ (see Section 4.3.7

on page 96).

Password Mode. In this mode, the “Break” bytes transmitted by the keyboard are discarded, and only the “Make” keystroke

bytes are compared with those programed in the PS2KEY0-7 registers. If the two sets are identical, a keyboard event that

sets KBD_EVT1_STS bit in GPE1_STS_2 register is detected (see Section 4.4.6 on page 102). The status bit is cleared

only when the software writes 1 to it. Only keys with a “Make” keystroke data of one byte can be included in the sequence

to be detected. To program the Keyboard/Mouse Wake-Up Detector to operate in Password mode:

1. Set KBDMODE field in KBDWKCTL register to ‘00’ (see Section 4.3.7 on page 96).

2. Set KBEVCFG field in PS2CTL register to a value that indicates the desired number of alphanumeric keystrokes in the

sequence. The programed value = the number of keystrokes + 7. For example, to detect a sequence of two keys, set

KBEVCFG to 09h.

3. Program the appropriate subset of the PS2KEY0-7 registers, in sequential order, with the “Make” data bytes of the keys

in the sequence. For example, if there are three keys in the sequence and the “Make” keystroke data of these keys are

05h (first), 50h (second) and 44h (third), program PS2KEY0 to 05h, PS2KEY1 to 50h and PS2KEY2 to 44h (the scan

codes are only examples).

Special Key Sequence Mode. In this mode, all the bytes transmitted by the keyboard (including “Make” and “Break” bytes)

are compared with those programed in the PS2KEY0-7 registers. If the two sets are identical, a keyboard event is detected,

as explained in Password Mode, above. Special Key Sequence mode enables the detection of any sequence of keystrokes,

including “Shift”, “Alt” and “Ctl” keys. To program the Keyboard/Mouse Wake-Up Detector to operate in Special Key Se-

quence mode:

1. Set KBDMODE field in KBDWKCTL register to ‘00’ (see Section 4.3.7 on page 96).

2. Set KBEVCFG field in PS2CTL register to a value that indicates the total number of bytes (“Make” and “Break”) in the se-

quence, minus 1 (i.e., the programed value = the number of bytes - 1). For example, to detect a sequence of three received

bytes (i.e., one keystroke), set KBEVCFG to 02h. The minimum value of the KBEVCFG field is 1 (i.e., two bytes).

3. Program the appropriate subset of the PS2KEY0-7 registers, in sequential order, with the data bytes that comprise the

sequence. For example, if the number of bytes in the sequence is four, and the values of these bytes are E0h (first), 5Bh

(second), E0h (third) and DBh (fourth), program PS2KEY0 to E0h, PS2KEY1 to 5Bh, PS2KEY2 to E0h and PS2KEY3

to DBh (the byte values are only examples).

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