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*** ''En'': enable
*** ''En'': enable
*** ''Clk'': clock
*** ''Clk'': clock
** outputs: 5-bit parallel address bus; 14-bit parallel code bus
** outputs
*** ''Addr'': 5-bit parallel address bus
*** ''Code'': 14-bit parallel code bus
* '''follow pulse'''
* '''follow pulse'''
** This block monitors the enable line generated by the 19-cycle hold block. At the end of the pulse it sees a falling edge and sends a single-cycle pulse to notify the terminal registers that the shift register has loaded a complete word and is ready to write.
** This block monitors the enable line generated by the 19-cycle hold block. At the end of the pulse it sees a falling edge and sends a single-cycle pulse to notify the terminal registers that the shift register has loaded a complete word and is ready to write.
=== Interface ===
=== Interface ===
The AD7314 temperature sensor uses a four-wire interface related to (and compatible with) the [http://en.wikipedia.org/wiki/Serial_Peripheral_Interface_Bus SPI bus] protocol. The wires are:
* ''CE'': Chip Enable (input), positive logic enable for ''SCLK''
* ''SCLK'': Serial Clock (input), clock line supplied by external source
* ''SDI'': Serial Data In (input), data input line
* ''SDO'': Serial Data Out (output), data output line
Note that the input/output notations are for slave devices (such as the temperature sensor) but are reversed for master devices (such as the FPGA). Proper SPI protocol flips the I/O polarity of ''CE'' and ''SCLK'' and crosses the ''SDI'' and ''SDO'' lines so that ''SDI'' is an input on every device and ''SDO'' is always an output. To maintain simplicity in wiring conventions we are not using proper SPI protocol, but are calling the slave input/master output line ''SDI'' and the slave output/master input line ''SDO'' so that the SDI/O notations are proper for slaves. The maximum clock rate is no higher than 10MHz. The interface, having separate input and output lines, is full-duplex; in fact the temperature sensor is unable to function in half-duplex mode. Outputs from the temperature sensor change on rising edges of ''SCLK'', but inputs are latched on falling edges.
=== Emulator ===
=== Emulator ===