Q3 Flashcards
What is an interupt?
When a microprocessor is told to stop doing what it’s doing and execute some other piece of software, the interupt routine.
What does UART stand for and what does it do?
Universal Asynchronous Receiver/Transmitter’s purpose is to convert data to and from a serial interface (where bits are sent one after another).
What is a common standard for serial interfaces?
RS-232: it’s used between computers and modems, or computers and mice.
What is a TXD on the UART?
A line for transmitting bits one after another
What is the RXD on the UART?
a line for receiving bits.
What do RTS and CTS stand for on the UART?
Request to send. Clear to send.
The RS-232 standard specifies that a 0 be represented by a ____ volts and a 1 by _____ volts.
+12 volts
-12 volts
What are the typical registers you might find in a UART?
A register into which the microprocessor writes bytes to be transmitted.
A register from which the microprocessor reads received bytes.
A register with a collection of bits that indicate any error conditions on received characters.
A register the microprocessor writes to tell the UART when to interrupt.
A register the microprocessor can read to find out why the UART interrupted.
True or False? UARTs contain a FIFO buffer.
True
What is the purpose of the FIFO buffer in a UART?
For data that is being received, relieving the requrement for your software to read one byte before the next one arrives.
What are Programmable Logic Devices, PLDs, used for?
They allow you to build more or less any glue circuit you want, i.e. 3-input nand gates where two inputs are inverted.
What are PALs?
PALs are the smallest PLDs that have 10 to 20 pins and an array of gates that you can hook up.
How can you hook up the connections among the PALs parts and pins?
With a PAL programmer
What do you need to know how the PAL works?
PAL equations: they describe what the PAL does.
On a PAL, what does the exclamation on the pin indicate.
That the signal is asserted low.
Show diagram of Inerupt Request Circuit. with four I/Os going into 3 IRQs.
Show diagram of a UART
