Extension modules • Simple display module •
This module offers on a small hole grid erection 8 LED's to display the state of each I/O line of a port. The LED's are connected with the anodes (+) over resistors to +5 V and with the cathode (-) directly to the port pins. The LED's light up at low-levels of the port pins (inverse display: 0=on, 1= off). This has been chosen due to the fact that the outputs of the MC's can deliver about 15 mA at a low-level and also most other digital circuits deliver most of the times a lot more power at low-level.
If you use low current LED's in this module you can use 1.5 kΩ resistors. The port outputs will have to supply about 2 mA. If you use regular LED's you should use 220 Ohm resistors. The port outputs will be burdened with about 14 mA which is already close to the limit.
There have been soldering pins (P0-P7) inserted at the port I/O pins of the module. At these soldering pins you can connect other consumers or sources if necessary. If you connect a soldering pin to a source like i.e. the output line of a digital gate, you should make sure that this corresponding port pin of the microcontrollers gets set on a high-level through the progam (in order to prevent that the MC with his relative strong low-signal does not drive against an eventual existing high-signal of the digital gate) and additionally you should consider that the digital gate in case of a low-signal at its output line not only has to pull its internal pullup-resistor to low but also has to supply the LED with energy.
Data
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Suitable for Experimenting BoardI and II
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Attachable to extension portCan be attached to any port
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Adjustments at DIP-switchNo special adjustments necessary. XTAL 1 and XTAL 2 should be "ON" so the MC gets a tact signal.
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Power consumptionDepending on the level at the port pins and the used LED's. With low current LED's 0 to 16 mA total, the 5 Volt line of the Experimenting Board gets burdened.
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Circuit board / LayoutVery simple layout. Optimized for set up on hole grid erection without bridges.
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LimitationsAt port 3 of the 20 Pin Flash MC's there is no port line 6. This of course is why D6 can't be triggered on that port.
Schematic
Schematic and Layout
For the schematic and layout plans you need the highly recommended schematic and layout editor EAGLE. A free english version can be downloaded at http://www.cadsoft.de/freeware.htm.
Simple display module Schematic and layout
File size: around 7 KByte
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