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GMS81C2112 Datasheet(PDF) 40 Page - Hynix Semiconductor |
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GMS81C2112 Datasheet(HTML) 40 Page - Hynix Semiconductor |
40 / 107 page ![]() GMS81C2112/GMS81C2120 34 JUNE. 2001 Ver 1.00 9. I/O PORTS The GMS81C21xx has five ports (R0, R2, R3, R5, and R6).These ports pins may be multiplexed with an alternate function for the peripheral features on the device. All pins have data direction registers which can define these ports as output or input. A “1” in the port direction register configure the corresponding port pin as output. Conversely, write “0” to the corresponding bit to specify it as input pin. For example, to use the even numbered bit of R0 as output ports and the odd numbered bits as input ports, write “55H” to address 0C1H (R0 port direction reg- ister) during initial setting as shown in Figure 9-1. All the port direction registers in the GMS81C2120 have 0 written to them by reset function. On the other hand, its in- itial status is input. Figure 9-1 Example of Port I/O Assignment RA(Vdisp) register: RA is one-bit high-voltage input only port pin. In addition, RA serves the functions of the Vdisp special features. Vdisp is used as a high-voltage input power supply pin when selected by the mask option. R0 and R0IO register: R0 is an 8-bit high-voltage CMOS bidirectional I/O port (address 0C0H). Each port can be set individually as input and output through the R0IO register (address 0C1H). Each port can directly drive a vacuum flu- orescent display. R03 port is multiplexed with Buzzer Out- put Port(BUZO), R02 port is multiplexed with Event Counter Input Port (EC0), and R01~R00 are multiplexed with External Interrupt Input Port(INT1, INT0) .The control register R0FUNC (address F4H) controls to select alternate function. After reset, this value is "0", port may be used as general I/O ports. To select alternate func- tion such as Buzzer Output, External Event Counter Input and External Interrupt Input, write "1" to the correspond- ing bit of R0FUNC. Regardless of the direction register R0IO, R0FUNC is selected to use as alternate functions, port pin can be used as a corresponding alternate features (BUZO, EC0, INT1, INT0) Port pin Alternate function RA Vdisp (High-voltage input power supply) I : INPUT PORT WRITE "55H" TO PORT R0 DIRECTION REGISTER 0 1 0 1 0 1 0 1 I O I O I O I O R0 data R1 data R0 direction R1 direction 0C0H 0C1H 0C2H 0C3H 7 65432 10 BIT 7654 3210 PORT O : OUTPUT PORT RA Data Register RA ADDRESS: 0FBH RESET VALUE: Undefined RA0 Input data Port Pin Alternate Function R00 R01 R02 R03 INT0 (External interrupt 0 Input Port) INT1 (External interrupt 1 Input Port) EC0 (Event Counter Input Port) BUZO (Buzzer Output Port) R0 Data Register R0 ADDRESS: 0C0H RESET VALUE: Undefined R07 R06 R05 R04 R03 R02 R01 R00 Port Direction R0 Direction Register R0IO ADDRESS : 0C1H RESET VALUE : 00H 0: Input 1: Output Input / Output data R0 Function Selection Register R0FUNC ADDRESS : 0F4H RESET VALUE : ----0000B 0: R00 1: INT0 0 0: R01 1: INT1 0: R02 1: BUZO 0: R03 1: EC0 1 2 3 - - - - |