COMSATS UNIVERSITY ISLAMABAD
MICROPROCESSOR SYSTEMS AND INTERFACING
LAB REPORT #12
SUBMITTED
TO:
SIR KHIYAM
IFTIKHAR
SUBMITTED
BY: -
|
S/NO |
NAME |
REG NO |
|
1 |
JUNAID AHMAD |
CIIT/FA19-BEE-089/ISB |
|
2 |
IBRAR AHMAD |
CIIT/FA19-BEE-083/ISB |
|
3 |
JARRAR MALIK |
CIIT/FA19-BEE-087/ISB |
DATE:
18-12-2021
Lab # 12: Interfacing Devices
using SPI
EXPLANATION ABOUT SPI:
Serial
Peripheral Interface (SPI) is an interface bus commonly used to send data
between microcontrollers and small peripherals such as shift registers,
sensors, and SD cards. It uses separate clock and data lines, along with a
select line to choose the device you wish to talk to. SPI works in a slightly
different manner. It’s a “synchronous” data bus, which means that it uses
separate lines for data and a “clock” that keeps both sides in perfect sync.
The clock is an oscillating signal that tells the receiver exactly when to
sample the bits on the data line. This could be the rising (low to high) or
falling (high to low) edge of the clock signal; the datasheet will specify
which one to use. When the receiver detects that edge, it will immediately look
at the data line to read the next bit.
In Lab Task:
SPI Programming in AVR:
The given
code contains functions to write bytes to SPI and writing to DAC. Your task is
to write code to send a sequence of numbers to the DAC to generate a saw-tooth
wave. Use gain =2x
CODE:
CIRCUIT DIAGRAM:
SIMULATIONS:
CRITICAL
ANALYSIS
In this lab
I learnt about the features and characteristics of SPI (serial peripheral
interfacing) which is used to communicate the microcontroller with registers
and SD cards. It has 4 lines or more which work synchronously. SPI consists of two shift or more
registers. One at master side, others at slave side. In SPI, only one side
generates the clock signal. The side that generates the clock is called the
“master”, and the other side is called the “slave”. There is always only one
master (which is almost always your microcontroller), but there can be multiple
slaves. When data is sent from the master to a slave, it’s sent on a data line
called MOSI, for “Master Out / Slave In”. moreover, I got to know that it works
in slave or master mode and in order to select these modes first we put the
values in CPOL and CPHA which are
actually bits of SPCR representing polarity and phase, also Digital to Analog
converter MCP4821 was used and it was
communicated through SPI protocol which produced a sawtooth waves as observed in lab task.
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