ST10F280 datasheet(73/186 Pages) STMICROELECTRONICS

73 / 186 page

ST10F280

73/186

12.1.2 - Input Threshold Control

The standard inputs of the ST10F280 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, Port4, 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, i.e. the 8-bit ports P7 and P8 are controlled by one bit each while ports P2 and P3 are controlled by

two bits each.

PICON (F1C4h / E2h)

ESFR

Reset Value:-00h

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 exter-

nal signals.

12.1.3 - Output Driver Control

The port output control registers POCONx allow to select the port output driver characteristics of a port.

The aim of these selections is to adapt the output drivers to the application’s requirements, and to

improve the EMI behaviour of the device. Two characteristics may be selected:

Edge characteristic defines the rise/fall time for the respective output, ie. the transition time. Slow edge

reduce the peak currents that are sinked/sourced when changing the voltage level of an external capaci-

tive load. For a bus interface or pins that are changing at frequency higher than 1MHz, however, fast

edges may still be required.

Driver characteristic defines either the general driving capability of the respective driver, or if the driver

strength is reduced after the target output level has been reached or not. Reducing the driver strength

increases the output’s internal resistance, which attenuates noise that is imported via the output line. For

driving LEDs or power transistors, however, a stable high output current may still be required.

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 28 : Hysteresis for Special Input Thresholds

Input level

Bit state

Hysteresis

ST10F280 数据表(PDF) 73 Page - STMicroelectronics

ST10F280 数据表(HTML) 73 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

数据表下载