Raspberry Pi - SPI Communication
You want to read all 8 channels of the MCP3008 and store their values in a dictionary with keys as channel numbers. Which code snippet correctly implements this using spidev?
You want to read all 8 channels of the MCP3008 and store their values in a dictionary with keys as channel numbers. Which code snippet correctly implements this using spidev?
hard🚀 Application Q15 of 15
Step-by-Step Solution
Solution:
Step 1: Understand correct SPI read and bit extraction
Each channel read requires one SPI transfer. The 10-bit value is extracted by maskingadc[1]with 3 and shifting before addingadc[2].Step 2: Check code correctness
values = {} for ch in range(8): adc = spi.xfer2([1, (8 + ch) << 4, 0]) values[ch] = ((adc[1] & 3) << 8) + adc[2] uses a for loop to read each channel once, extracts the value correctly, and stores it in a dictionary with channel keys.Final Answer:
Option B code snippet -> Option BQuick Check:
Loop + mask adc[1] & 3 + shift + store in dict [OK]
Quick Trick: Use a loop with masking and shifting to read all channels [OK]
Common Mistakes:
MISTAKES- Calling spi.xfer2 twice per channel (Option A)
- Not masking adc[1] bits (Option D)
- Storing raw SPI response without processing (Option C)
Master "SPI Communication" in Raspberry Pi
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