Motorola Axiom CMD11E1 Guía de usuario descargar pdf (Pagina 46)

46 CHAPTER 3. FUNCTIONS AND BIT MANIPULATIONS

drive devices from these pins (as long as you do not supply more than 5 mA). PA7

is bidirectional and you, as the programmer, can conﬁgure the pin as either input

or output.

WARNING: You may have wired the port as input and either by accident or

oversight, may set the pin as an output pin. This can seriously damage the pin

if the pin carries currents in excess of 5 mA or so. To prevent the damage, make

sure there is a current limiting resistor (4.7K) in series with the pin. This warning

is applicable to any pin that is bidirectional.

WARNING: If you lend your HC11 to anyone, make sure you disconnect any

circuit that may be connected to PA7.

Special instructions for CMD11E1 users

1. Locate the jumper JP13 and make sure that it is open.

2. Locate the MCU port. This is a dual row 34-pin Berg style connector.

Locate pin #1 on the port. This is identiﬁed with the number 1 on the

front of the board. On the other side (solder side), pin #1 is identiﬁed by a

square solder.

3. Connect a ribbon cable to the port. Use a continuity tester to locate and

identify the following pins: pin 1 (PA0), pin 5 (PA4), pin 6 (PA5), pins 9

and 10 (5 Volts), pins 11 and 12 (Ground). (See page 15 of the User’s guide

that came with your board.)

4. Make two test light emitting diode probes. It is a good idea to have several

probes handy. To make a test probe, connect a 3.3K resistor to the anode

of a light emitting diode (See ﬁgure 3.1). Use a light emitting diode with

an operating voltage of 1.7 volts and a current rating in the 1-5 mA range.

If you use an light emitting diode with 20+ mA operating current, the light

emitting diode would be dim when it lights up and you may have to look

carefully to see if it is on. Test the probe by connecting the free end of

the resistor to pin 9 and the free end of the light emitting diode to pin 11.

The light emitting diode should light-up. If not, the chances are you have

connected the resistor to the cathode of the light emitting diode. Redo your

circuit by connecting the resistor to the anode.

5. Connect a (LEFT) test probe between pin 5 and pin 11. The cathode of the

light emitting diode should be connected to pin 11 and the free end of the

resistor to pin 5.

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Motorola Axiom CMD11E1 Guía de usuario Pagina 46