PV198 - SPI II
One-chip Controllers
Daniel Dlhopolček, Marek Vrbka, Jan Koniarik, Oldřich Pecák,
Tomáš Rohlínek, Ján Labuda, Jan Horáček, Matúš Škvarla, Ondřej Bleha,
Martin Klimeš, Adam Valt
Faculty of Informatics, Masaryk University
9/2024
Introduction
Intro
Switch the branch to Week_09!
Discussion of HW8
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Task
Context
In some cases it is necessary to serve not to rule.
We will be implementing a simple SPI slave device.
When request is received from the master, send data back:
Reading the data from sensor is slow → they have to be prepared
in advance.
We will be using non-blocking SPI API.
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Task
Requirements
Master can send two types of messages (identified by the initial byte
of the message):
1. send_ADC (0x55): report latest measured ADC value.
2. receive_UART (0xCC): print 16 subsequent bytes to UART.
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Task
Template
Template provides an example of the API to use and basic solution
structure.
1. DSPI_SlaveUserCallback
This function is called by the driver after a transfer is finished
(similar to interrupt).
2. DSPI_SlaveTransferNonBlocking
This function passes data to the driver, which then transfers it to
the master when required.
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Task
Raspberry PI pico
We will be using RPI pico as the SPI master.
RPI pico runs MicroPython with functions preloaded on the board:
print_on_UART()
read_ADC()
read_count()
Source code in the IS: main.py.
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Task
Wiring
Make connection in this exact order:
1. Connect pins between K66 and RPI.
2. Connect K66 to PC using USB.
3. Connect RPI to PC using USB.
Wrong order can damage the board!
RPI pico FRDM-K66P
GND GND
GP2 PTD1
GP3 PTD3
GP4 PTD2
GP5 PTD0
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Task
Counter
Every response from slave to master will start with a byte containing
the counter.
1. Every time you finish either receive_UART or send_ADC
operation, increment the counter.
2. Count is represented by an 8bit unsigned number. It can
overflow.
3. Repeated comunication with neither send_ADC nor
receive_UART does not affect the counter.
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Task
send_ADC
Read ADC value:
1. Respond with values from ADC1 SE_13.
(for inital testing use a constant value)
2. Read command is identified by value 0x55.
3. Expected ADC value is Big Endian, 12bit long.
4. Prepare ADC value in advance.
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Task
receive_UART
Receive 16 bytes over SPI, then send them over UART.
1. Configure PTB11 as UART3_TX.
2. Write command is identified by value 0xCC.
3. You will recieve a chunk of 16 bytes. After you get them all, print
your data to UART.
4. Beware: blocking transmit on UART might give you problems in
callback.
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Task
Example
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Task
Homework
Finish assignment for the lesson.
Scope of lesson is deliberately larger.
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Task
Bonus
Recieve chunks of 3 bytes.
1. Configure PTB10 as UART3_RX.
2. Write command is initialized by value 0x37.
3. You will be asked to return 3 bytes stored, that you recieved by
UART3_RX.
4. If there were no data stored, return random data but do not
increment counter.
5. Make internal memory 64messages long. If more massages
recieved, overwrite the oldest one.
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