Hallo everyone,
I'm Gabriel. I'm new to this world. I used to spend time in analog electronic and now I feel a bit confused by some tutorials about logic digital signals.
My goal is to sense sensors (gas sensor and DHT22) with Arduino Nano and show the result on a LCD2004 display.
My second goal is to do the same in Raspberry Pi environment.
The tutorial I've found is this.
But something doesnt convince me.
ARDUINO (Analog/Digital 5V)
CASE1:
- gas sensor (A/D output avaible) @5V
- analog signal from MQ-7 to Analog GPIO
CASE2:
- gas sensor (A/D output avaible) @5V
- digital signal from MQ-7 to Digital GPIO
CASE3:
- gas sensor (A/D output avaible) @5V
- analog signal from MQ-7 to MCP3008
- MCP3008 via SPI (digital) to GPIO
RASPBERRY (Digital 3.3V)
CASE1:
- gas sensor (A/D output avaible) @5V
- digital signal passes to level shifter 5V->3.3V
- 3.3V digital signal to Digital GPIO
CASE2A (TUTORIAL):
- gas sensor (A/D output avaible) @5V
- digital signal passes to level shifter 5V->3.3V
- 3.3V digital signal to MCP3008
(why?? Just to achieve 8 channel - 8 sensor - using just 4 pin SPI comunication? if i have 1 sensor is useless to use a MCP3008 like that?) - MCP3008 via SPI (digital) to GPIO
CASE2B (TUTORIAL if sensor signal type is analog but wrong labeled in images):
- gas sensor (A/D output avaible) @5V
- analog signal (???) pass to level shifter 5V->3.3V (is it possible???)
- 3.3V analog signal to MCP3008
- MCP3008 via SPI (digital) to GPIO
Can you help me to understand how things going in the tutorial schematic?
