LED光立方制作全过程（二十一）
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发表于 5/4/2011 8:49:43 AM
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Step 36Build the controller: Connect the ICs, 8bit bus + OE
In the picture, you'll notice a lot of wires have come into place.
All the tiny blue wires make up the 8+1bit bus that connects all the latch ICs. 8 bits are for data, and the +1 bit is the output enable line.
At the top of the board, we have added a 16 pin connector. This connects the latch board to the micro controller board. Next to that, you see the 74HC138.
The tiny blue wires are Kynar wire. This is a 30 or 32 AWG (american wire gauge) wire. Very tiny. We love working with this type of wire. Because it is so thin, it doesn't take up that much space on the circuit board. If we had used thicker wire, you wouldn't be able to see the board through all the wires. Kynar wire is coated with tin, so you can solder directly after stripping it. No need for pre-tinning. The tiny blue wires are connected to the same pin on every latch IC.
From the connector at the top, you can see 8 green wires connected to the bus. This is the 8 bit data bus. We used different colors for different functions to better visualize how the circuit is built.
The orange wire connected to the bus is the output enable (OE) line.
On the right hand side of the connector, the first pin is connected to ground.
All the tiny blue wires make up the 8+1bit bus that connects all the latch ICs. 8 bits are for data, and the +1 bit is the output enable line.
At the top of the board, we have added a 16 pin connector. This connects the latch board to the micro controller board. Next to that, you see the 74HC138.
The tiny blue wires are Kynar wire. This is a 30 or 32 AWG (american wire gauge) wire. Very tiny. We love working with this type of wire. Because it is so thin, it doesn't take up that much space on the circuit board. If we had used thicker wire, you wouldn't be able to see the board through all the wires. Kynar wire is coated with tin, so you can solder directly after stripping it. No need for pre-tinning. The tiny blue wires are connected to the same pin on every latch IC.
From the connector at the top, you can see 8 green wires connected to the bus. This is the 8 bit data bus. We used different colors for different functions to better visualize how the circuit is built.
The orange wire connected to the bus is the output enable (OE) line.
On the right hand side of the connector, the first pin is connected to ground.
Step 37Build the controller: Address selector
The 74HC138 is responsible for toggling the clock pin on the 74HC574 latch ICs. We call this an address selector because it selects which one of the 8 bytes in the latch array we want to write data to. The three blue wires running from the connector to the 74HC138 is the 3 bit binary input used to select which of the 8 outputs is pulled low. From each of the outputs on the 74HC138, there is a wire (white) running to the clock pin on the corresponding 74HC574 latch IC.
Start by soldering the GND and VCC connections. If you use the solder trace method to run GND/VCC lines you want to do this before you solder any other wires in place. A 100nF ceramic filtering capacitor is placed close to the VCC and GND pins of the 74HC138.
Then connect the address lines and the 8 clock lines.
If you look carefully at the connector, you can see two pins that are not used. These will be used for a button and debug LED later.
Start by soldering the GND and VCC connections. If you use the solder trace method to run GND/VCC lines you want to do this before you solder any other wires in place. A 100nF ceramic filtering capacitor is placed close to the VCC and GND pins of the 74HC138.
Then connect the address lines and the 8 clock lines.
If you look carefully at the connector, you can see two pins that are not used. These will be used for a button and debug LED later.
