ST52T400 datasheet(47/94 Pages) STMICROELECTRONICS

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ST52T400/T440/E440/T441

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6.2 Input Mode

The input configuration is selected setting the cor-

responding

configuration

bit

REG_CONF4, REG_CONF13 and, where appli-

cable, REG_CONF11 (see Paragraph I/O Port

Configuration Registers) to “1”. To use Port A and

B pins as digital input, the corresponding bits in

REG_CONF12 and REG_CONF14 must be set

according to the values shown in Table 6.4, Table

6.5 and Table 6.6.

(*) Not used for ST52x400F/440F/441F

Digital input data is automatically stored in

the Input Registers (see Table 6.2), but the single

bit of the Input Register (IR) cannot be read

directly and the value in a RAM location must be

copied. Digital data is stored in a RAM location by

using the assembler instruction:

LDRI regx,inpy

Then, each single bit can be examined by using

AND and OR operators with a suited mask value.

6.3 Output Mode

The output pin configuration is selected by setting

the corresponding configuration register bit to “0”

(REG_CONF4, REG_CONF13 and, where appli-

cable, REG_CONF11) (see paragraph I/O Port

Configuration Registers). in order to use Port A

and B pins as digital output, the corresponding bits

in REG_CONF12 and REG_CONF14 must be set

according to the values illustrated in Tables - Port

A - REG_CONF 4, - Port A - REG_CONF 12 and

Analog Inputs REG_CONF 14.

Digital data is transferred to the related I/O Port by

means of the Output register (see Table 6.3), by

using the assembler instructions LDPE or LDPR

that respectively take the value to be transferred

to the ports from EPROM and RAM.

Figure 6.2 Port B Functional Blocks

TO A/D CONVERTER

CMOS

PORT B PIN

FROM CONFIGURATION REGISTER

TO INPUT REGISTER

FROM OUTPUT REGISTERS

FROM CONFIGURATION REGISTER

22 k

Vcc

Table 6.2 Input Register and I/O Ports

PORT A

PORT B

PORT C (*)

IR 14

IR 15

IR 16

Table 6.3 Output Register and I/O Ports

PORT A

PORT B

PORT C (*)

OR 0

OR 1

OR 2

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