PC87373 datasheet(83/174 Pages) NSC

83 / 174 page

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

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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 6.4.6 on page 100). 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 6.3.7 on page 94).

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 6.3.7 on page 94).

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).

Special Key Sequence mode also enables detection of any single keystroke. To program the Keyboard/Mouse Wake-Up

Detector to wake-up on any single keystroke:

1. Set KBDMODE field in KBDWKCTL register to ‘00’ (see Section 6.3.7 on page 94).

2. Set KBEVCFG field in PS2CTL register to ‘0001’.

3. Program the PS2KEY0 and PS2KEY1 registers to 00h. This forces the detector to ignore the values of incoming data,

thus causing it to detect a keyboard event caused by a single keystroke.

Power Management Mode. In this mode, the PS2KEY0-7 register bank is divided into three groups of registers:

PS2KEY0-2, PS2KEY3-5 and PS2KEY6-7. Each group can be programed with different data bytes, allowing the bytes trans-

mitted by the keyboard to be compared simultaneously with three keystroke sequences. If the bytes transmitted by the key-

board (including Make and Break) are identical to the data bytes in one register group, the related keyboard event is

detected. The detection of Keyboard Event 1 (data in PS2KEY0-2) sets KBD_EVT1_STS bit; the detection of Keyboard

Event 2 (data in PS2KEY3-5) sets KBD_EVT2_STS bit; the detection of Keyboard Event 3 (data in PS2KEY6-7) sets

KBD_EVT3_STS bit. All three status bits are in GPE1_STS_2 register (see Section 6.4.6 on page 100). Each status bit is

cleared only when the software writes 1 to the bit. This mode enables the detection of any sequence of keys.

To program the Keyboard/Mouse Wake-Up Detector to operate in Power Management Keys mode, proceed as follows:

1. Set KBDMODE field in KBDWKCTL register to ‘10’ (see Section 6.3.7 on page 94).

2. Set each event configuration field (EVT1CFG, EVT2CFG and EVT3CFG) in KBDWKCTL register to a value that indi-

cates the desired number of keystroke data bytes (“Make” and “Break” bytes) in the sequence, for each event. For ex-

ample, to detect a sequence of two received bytes, set EVTxCFG to 02h.

3. Program each group of the PS2KEY0-7 registers, in sequential order, with the data bytes of the keys in the sequence

for each event.

Event Generation. Keyboard event detection from KBCLK and KBDAT is enabled, for event generation, tEWIV after VSB3

power is on (see Wake-Up Inputs at VSB3 Power Switching on page 173). This prevents the detection of false Keyboard

events during VSB3 power-On transitions.

Usage Hints:

1. After changing the operation mode of the Keyboard/Mouse Wake-Up Detector, clear the KBD_EVT3_STS,

KBD_EVT2_STS, KBD_EVT1_STS, and KBD_ANYK_STS status bits in GPE1_STS_2 register (see Section 6.4.6 on

page 100).

2. If a byte sequence that is a “subset” of the byte sequence of another (“superset”) Power Management key event is used,

the “superset” Power Management key event will never be detected. (The subset sequence has fewer bytes, set by

EVTxCFG fields in KBDWKCTL register, than the superset sequence; however, the bytes contained in the subset se-

quence, as programed in the PS2KEY0-7 registers, are identical to the respective bytes of the superset sequence.)

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