Version 1.0 8-1Chapter 8General PurposeInput/OutputThe LH79524 and LH79525 have a robust set of General Purpose Input/Output (GPIO)pins that can be used for any required input or output function. The LH79524 has 14 ports,providing 108 pins of GPIO. The LH79525 has 11 ports, with 86 individual pins. All descrip-tions, unless noted, apply to both the LH79524 and LH79525.8.1 Theory of OperationThe GPIO pins are multiplexed with other functions. Some of the GPIO ports haveSchmitt triggers, and some have pull-up or pull-down resistors built in (See Table 8-2).Table 8-1 summarizes the configuration of each port. Note that Port J is input only, andPort M is output only. At reset, all ports except Ports J and M are configured for input. PortsJ and M are not configured as GPIO at reset.8.1.1 Port ConfigurationPort pins can be configured individually as inputs or outputs (except, of course, Ports J andM). The direction of each pin is programmed using the Data Direction Registers (P1DDRxand P2DDRx). Data for output pins is written to the port Data Register (P1DRx andP2DRx). Input data is read from the same registers.Table 8-1. GPIO PortsPORT LH79524 GPIO LH79525 GPIOA 8 Input/Output Pins 8 Input/Output PinsB 8 Input/Output Pins 8 Input/Output PinsC 8 Input/Output Pins 8 Input/Output PinsD 8 Input/Output Pins 8 Input/Output PinsE 8 Input/Output Pins 8 Input/Output PinsF 8 Input/Output Pins 8 Input/Output PinsG 8 Input/Output Pins 8 Input/Output PinsH 8 Input/Output Pins 8 Input/Output PinsI 8 Input/Output Pins 8 Input/Output PinsJ 8 Input Pins 8 Input PinsK 8 Input/Output Pins Not AvailableL 8 Input/Output Pins Not AvailableM 8 Output Pins 6 Output PinsN 4 Input/Output Pins Not Available
