HCS12 9S12 PDF

This is not something for learning embedded programming. If you should consider yourself a novice, we recommend you purchase the Dragon12 Plus2 instead. Verify monitor type on your Thunderbiard board: If your module is pre-installed with Freescale bootloader and D-Bug12 monitor, the states of the 2-position DIP switch S2 are tested by the bootloader for selecting one of 4 operating modes during power up or reset, and the 4 LED indicators will light up from left to right to indicate that the bootloader is functioning. Then one of them will be lit to indicate the selected operating mode and other three will be turned off.

Author:Nidal Vojind
Country:Saudi Arabia
Language:English (Spanish)
Genre:Medical
Published (Last):23 December 2010
Pages:34
PDF File Size:19.78 Mb
ePub File Size:4.34 Mb
ISBN:651-6-24140-370-9
Downloads:34209
Price:Free* [*Free Regsitration Required]
Uploader:Faegis



Input pin logic levels and threshold voltages Pins on the HCS12 configured as digital inputs are guaranteed to report a logical high if the input voltage is greater than 0. They will always report a logical low if the input voltage is less than 0. Input voltages between 1. The trigger voltage can lie anywhere within the 1. The consequence of this hysteresis is that the threshold between a logic high and a logic low depends on whether the input voltage is rising or falling.

The following diagram shows the measured threshold for a single pin. When the input voltage rises from a logic 0 toward a logic 1 level, the logic 1 is recognized when the voltage rises to 2. Negative going noise on the input voltage will not cause a false transition back to a logic 0 unless it is greater than 0. Likewise, during a logic 1 to logic 0 transition, the input is protected against positive going noise spikes of less than 0.

The actual threshold values and degree of hysteresis will vary from pin to pin. The hysteretic input works together with any source impedance driving the pin to provide some immunity against noise and to debounce the input signal.

Full drive mode is recommended for most applications. No action is required to obtain full drive, as this is the default condition after a reset. In the low state, full-drive digital outputs can keep the voltage below 0. Load circuitry that requires significant current to be sourced or sunk by the digital output should include external resistors to ensure that the absolute maximum rating of 25 mA per output pin is never exceeded.

That is, for currents of less than 10 mA the voltage change is linear with current; it can be modeled as a voltage source of either zero or five volts and an equivalent series resistance of 40 ohms 1.

At greater output currents the resistance increases gradually, but the 40 ohm approximation holds good up through the 25 mA maximum. The following graphs illustrate the variation. The resistor limits the current into the LED.

From the LED datasheet we note that its forward voltage at a current of 10 mA is specified to be 2. What should the resistor value be? We calculate it as, Eqn. Plugging 4. You may either source current to the LED, or sink current from it, as shown in the following circuit. You may use the HCS12 microcontroller output pin as either a high-side or low-side driver for an LED 9S12 output pin voltage vs current in full drive mode The following graphs show that the resistance of an output pin in either the high or low state is approximately 40 ohms for currents to the maximum of 25 mA.

The maximum current you should ever source from the pin is 25 ma. The maximum current you should ever sink with the pin is 25 ma.

Protecting the 9S12 input and output pins These digital output pins are very useful because they can directly drive a wide range of devices. Nevertheless, any circuitry connected to the processor should take care to: Prevent excessive voltage levels at the pin; and, Prevent excessively great currents. They consist of internal diodes that conduct current from the input pin to the supply or ground rails in the event that the input pin voltage exceeds the supply range.

However, you should not rely on the internal diodes to prevent damage from excessive voltage. Excessive voltages are prevented by ensuring that voltages of less than a diode drop below VSS that is, For some applications, particularly when driving inductive loads such as relays, you may need to provide Schottky diode clamps between the pin and VDD and between the pin and ground.

If there is the possibility of the output pin being driven to a negative voltage level it is better to prevent excessive power dissipation in the processor package by externally clamping the voltage to ground VSS with a Schottky diode.

Preventing excessive currents The current into or out of any pin on the MCHCS12 should also be limited to prevent damage. The specified maximum instantaneous current is 25 mA into or out of any one pin at a time.

Pin currents must be limited using external resistors.

JUS IEC 1024 1 PDF

Freescale HCS12 9S12 Datasheets

Input pin logic levels and threshold voltages Pins on the HCS12 configured as digital inputs are guaranteed to report a logical high if the input voltage is greater than 0. They will always report a logical low if the input voltage is less than 0. Input voltages between 1. The trigger voltage can lie anywhere within the 1. The consequence of this hysteresis is that the threshold between a logic high and a logic low depends on whether the input voltage is rising or falling.

JORGE RUFFINELLI PDF

Digital I/O - Hardware Interfacing

Observe the 8 port B LED indicators. If the chirp is too soft you can remove the label sticker on the speaker to increase volume. If you ordered the board with serial monitor firmware for the CodeWarrior, it would be pre-installed with the serial monitor and a factory test program. If the left switch is placed in the "LOAD" mode in the "low" position the monitor will wait for a command from the host PC. If the left switch is placed in the "RUN" mode in the "up" position the 8 port B LED indicators will flash again from left to right to indicate that the program execution is diverted to the user code. If monitor firmware is not installed or is erased by a BDM, the 8 port B LED indicators will not flash sequentially during power up or reset. The driver for the CHG will be automatically installed by Win

GAZWA TABUK IN URDU PDF

Digital I/O - Hardware Interfacing

.

ASKEP GGK NIC NOC PDF

Motorola 68HC12

.

Related Articles