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P87LPC779 Fiches technique(PDF) 33 Page - NXP Semiconductors |
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P87LPC779 Fiches technique(HTML) 33 Page - NXP Semiconductors |
33 / 74 page Philips Semiconductors P87LPC779 CMOS single-chip 8-bit microcontroller Product data Rev. 02 — 03 May 2004 33 of 74 9397 750 13213 © Koninklijke Philips Electronics N.V. 2004. All rights reserved. 8.9.4 Keyboard interrupt (KBI) The Keyboard Interrupt function is intended primarily to allow a single interrupt to be generated when any key is pressed on a keyboard or keypad connected to specific pins of the P87LPC779, as shown in Figure 13. This interrupt may be used to wake up the CPU from Idle or Power-down modes. This feature is particularly useful in handheld, battery powered systems that need to carefully manage power consumption yet also need to be convenient to use. The P87LPC779 allows any or all pins of port 0 to be enabled to cause this interrupt. Port pins are enabled by the setting of bits in the KBI register, as shown in Tables 23 and 24. The Keyboard Interrupt Flag (KBF) in the AUXR1 register is set when any enabled pin is pulled LOW while the KBI interrupt function is active. An interrupt will be generated if it has been enabled. Note that the KBF bit must be cleared by software. Due to human time scales and the mechanical delay associated with keyswitch closures, the KBI feature will typically allow the interrupt service routine to poll port 0 in order to determine which key was pressed, even if the processor has to wake up from Power-down mode. Refer to Section 8.12 “Power reduction modes” on page 38 for details. Fig 13. Keyboard interrupt. Table 23: KBI - Keyboard interrupt register (address 86H) bit allocation Not bit addressable; Reset value: 00H Bit 7 6 5 4 3 2 1 0 Symbol KBI.7 KBI.6 KBI.5 KBI.4 KBI.3 KBI.2 KBI.1 KBI.0 002aaa631 P0.7 KBI.7 P0.6 KBI.6 P0.5 KBI.5 P0.4 KBI.4 P0.3 KBI.3 P0.2 KBI.2 P0.1 KBI.1 P0.0 KBI.0 KBF (KBI interrupt) EKB (from IEN1 register) |
Numéro de pièce similaire - P87LPC779 |
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Description similaire - P87LPC779 |
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