Two ports, one 6 bit control port and one 8 bit io port. The power up reading of the control port (with weak pull up's) tells the UNIO what mode to operate in. Modes that do not use all 6 control port lines are identified because they have the left over lines pulled (or jumpered) low on the circuit board.
initial reading |
Signals | Mode | Notes |
111111 | En, Addr, Data[4] | 4 bit by two addressable latch | |
011111 | -, Addr, Data[4] | 4 bit by two addressable latch | Lack of clock is compinsated for by watching all lines for 0.5 clock cycles after any change is detected and updateing output pins only after this "settleing time" |
1110 11 | En, Data[2], -, Addr[2] | 2 bit by four addressable latch | |
0110 11 | -, Data[2], Addr[2] | 2 bit by four addressable latch | |
101 111 | En, -, Data, Addr[0..3] | 1 bit by eight addressable latch | |
010 111 | -, Data, -, Addr[0..3] | 1 bit by eight addressable latch | |
1111 10 | SCK, SI, SO, *CE, 1, 0 | SPI | |
1011 10 | SCK, -, SI+SO, CE, 1, 0 | SPI (3 pin) | SO connected to SI thru resistor |
1111 00 | SCK, SI, SO, CE, 0, 0 | SPI <-> Serial | RX, TX, *CE, are the first three pins of the 8 bit IO port |
1111 01 | SCK, SI, SO, CE, 0, 1 | SPI <-> I2C | SCL, SDA, -, *CE are the first four pins of the 8 bit IO port. |
1100 01 | SCL, SDA, -, -, 0, 1 | I2C | Basically a shift register |
1101 01 | SCL, SDA, -, *CE, 0, 1 | I2C with *CE | Several shift registers connect to the same data and clock lines with seperate chip selects |
1111 01 | SCL, SDA, CLR, *CE, 0, 1 | I2C with *CE and CLR | Shift register with enable and clear. |
1101 00 | SCL, SDA, -,*CE, 0 , 0 | I2C <-> Serial | Allows us to debug I2C interfaces.
|
0100 00 | -, TX, -, -, 0, 0 | Serial Out | |
1000 00 | RX, -, -, -, 0, 0 | Serial In | |
0110 00 | -, TX,*CE, -, 0, 0 | Serial Out with *CE | |
1010 00 | RX, -, *CE, -, 0, 0 | Serial In with *CE | |
1100 00 | RX, TX, -, -, 0, 0 | Serial IO | |
1110 00 | RX, TX, *CE, -, 0, 0 | Serial IO with *CE | |
Notice that the first line of the 6 bit control port is the IRQ line.
file: /Techref/idea/unio.htm, 4KB, , updated: 2002/5/6 16:26, local time: 2024/8/14 14:32,
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