Cypress Semiconductor FX2LP Przewodnik Instalacji Pobierz pdf (Strona 19)

EZ-USB Development Board Page -15

U9 has the group address 0100, and is strapped to unit address 000. Therefore to read the switch

values, 8051 firmware sends a control byte of 01000001 (the LSB indicates a read operation), and

then reads the data byte.

4.10 Indicators—Power and Breakpoint

LED D1 is connected to the PCB 5 volt supply, which is normally supplied from the USB cable

(VBUS pin). Alternatively, JP2 may be removed and external 5 volt power can be applied to JP2

pin 1. In either case, D1 indicates the presence of the 5 volt power.

LED D6 is connected to the 3.3 volt voltage regulator output.

LED D7 is connected to the EZ-USB BKPT (Breakpoint) pin. When using the Keil software devel-

opment tools, this green LED indicates that the EZ-USB Development Board has enumerated,

and the Keil monitor has loaded and started running.

4.11 General Purpose Indicators

A portion of the GAL (U2) decodes 8051 reads to certain external memory addresses to turn the

four general-purpose indicators D2-D5 on and off. The following figure shows the positions of the

four indicator LEDS, and a table of the external 8051 addresses which are read to turn them on

and off. Note that the four jumpers above the LEDS must be installed to use this feature. These

jumpers connect the LEDS to four GAL outputs.

Note: The CLKOUT signal is used as a clock to latch the LED output signals from the GAL. If

CLKOUT is disabled, the LEDs will not update.

NOTE: If you wish to use the LEDS for other purposes, for example to wire to other PC board sig-

nals for observation, first remove the shorting plug to disconnect the LED from the GAL. The LED

terminal is the bottom pin of the connector, and the GAL I/O pin is the top pin.

Bit Switch

0S2

1S3

2S4

3S5

1 2 ... 14 15 16 17 18 19 20 21 22 23 24 ... 27 28

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Cypress Semiconductor FX2LP Przewodnik Instalacji Strona 19