ST10F269ZX datasheet(59/184 Pages) STMICROELECTRONICS

59 / 184 page

ST10F269

12 - PARALLEL PORTS

59/184

12.2 - I/O’s Special Features

12.2.1 - Open Drain Mode

Some of the I/O ports of ST10F269 support the

open drain capability. This programmable feature

may be used with an external pull-up resistor, in

order to get an AND wired logical function.

This feature is implemented for ports P2, P3, P4,

P6, P7 and P8 (see respective sections), and is

controlled through the respective Open Drain

Control Registers ODPx. These registers allow

the individual bit-wise selection of the open drain

mode for each port line. If the respective control

bit ODPx.y is ‘0’ (default after reset), the output

driver is in the push-pull mode. If ODPx.y is ‘1’, the

open drain configuration is selected. Note that all

ODPx registers are located in the ESFR space

(See Figure 19).

12.2.2 - Input Threshold Control

The standard inputs of the ST10F269 determine

the status of input signals according to TTL levels.

In order to accept and recognize noisy signals,

CMOS-like input thresholds can be selected

instead of the standard TTL thresholds for all pins

of Port 2, Port 3, Port 4, Port 7 and Port 8. These

special thresholds are defined above the TTL

thresholds and feature a defined hysteresis to

prevent

the

inputs

from toggling

while

the

respective input signal level is near the thresholds.

The Port Input Control register PICON is used to

select these thresholds for each Byte of the

indicated ports, this means the 8-bit ports P4, P7

and P8 are controlled by one bit each while ports

P2 and P3 are controlled by two bits each.

All options for individual direction and output mode

control are available for each pin, independent of

the selected input threshold. The input hysteresis

provides stable inputs from noisy or slowly

changing external signals (See Figure 20).

PICON (F1C4h / E2h)

ESFR

Reset Value: --00h

9876543210

--------

P8LIN P7LIN

P4LIN P3HIN P3LIN P2HIN P2LIN

Bit

Function

PxLIN

Port x Low Byte Input Level Selection

Pins Px.7...Px.0 switch on standard TTL input levels

Pins Px.7...Px.0 switch on special threshold input levels

PxHIN

Port x High Byte Input Level Selection

Pins Px.15...Px.8 switch on standard TTL input levels

Pins Px.15...Px.8 switch on special threshold input levels

Figure 19 : Output Drivers in Push-pull Mode and in Open Drain Mode

Push-Pull Output Driver

Open Drain Output Driver

External

Pullup

ST10F269ZX データシート(PDF) 59 Page - STMicroelectronics

ST10F269ZX データシート(HTML) 59 Page - STMicroelectronics

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

データシートダウンロード