RP Zero W GPIO

[MShemet]

Hi guys. Please help!

Need help with GPIO. I have 21 sensors connected to the RP Zero W and I’m not sure which GPIO is best for which sensor.

I have:
- 7 thermistors
- 5 Ammeter
- 4 pcs 5/110VAC really
- 3 buttons (open / close)
- 1 pressure sensor
- 1 wet sensor.

Thank you in advance!

[FTrevorGowen]

Hi guys. Please help!

Need help with GPIO. I have 21 sensors connected to the RP Zero W and I’m not sure which GPIO is best for which sensor.

I have:
- 7 thermistors
- 5 Ammeter
- 4 pcs 5/110VAC really
- 3 buttons (open / close)
- 1 pressure sensor
- 1 wet sensor.

Thank you in advance!

More detailed info. is needed especially w.r.t the thermistors, ammeters, pressure sensor and "wet sensor". If any of those devices are "analogue" rather than using I2C, SPI or serial or other digital interface they cannot be used directly with a Pi - it doesn't have any analogue inputs. (The only things in your list that can be regarded as "digital" are the buttons and relays and the latter will require a "buffer circuit" such as a transistor switch or, better, an opto-isolator.) Some GPIO's can be "dedicated" to I2C, SPI, Serial or interfaces/protocols the rest are mainly for input or output logic ie. don't have special, predefined hardware, alt(ternative) functions. The table below gives some indication of what can be setup - I have the I2C, SPI and serial interfaces enabled:

Code: Select all

pi@raspiP4B4b-32GbP:~ $ gpio readall
 +-----+-----+---------+------+---+---Pi 4B--+---+------+---------+-----+-----+
 | BCM | wPi |   Name  | Mode | V | Physical | V | Mode | Name    | wPi | BCM |
 +-----+-----+---------+------+---+----++----+---+------+---------+-----+-----+
 |     |     |    3.3v |      |   |  1 || 2  |   |      | 5v      |     |     |
 |   2 |   8 |   SDA.1 | ALT0 | 1 |  3 || 4  |   |      | 5v      |     |     |
 |   3 |   9 |   SCL.1 | ALT0 | 1 |  5 || 6  |   |      | 0v      |     |     |
 |   4 |   7 | GPIO. 7 |   IN | 1 |  7 || 8  | 1 | ALT5 | TxD     | 15  | 14  |
 |     |     |      0v |      |   |  9 || 10 | 1 | ALT5 | RxD     | 16  | 15  |
 |  17 |   0 | GPIO. 0 |   IN | 0 | 11 || 12 | 0 | IN   | GPIO. 1 | 1   | 18  |
 |  27 |   2 | GPIO. 2 |   IN | 0 | 13 || 14 |   |      | 0v      |     |     |
 |  22 |   3 | GPIO. 3 |   IN | 0 | 15 || 16 | 0 | IN   | GPIO. 4 | 4   | 23  |
 |     |     |    3.3v |      |   | 17 || 18 | 0 | IN   | GPIO. 5 | 5   | 24  |
 |  10 |  12 |    MOSI | ALT0 | 0 | 19 || 20 |   |      | 0v      |     |     |
 |   9 |  13 |    MISO | ALT0 | 0 | 21 || 22 | 0 | IN   | GPIO. 6 | 6   | 25  |
 |  11 |  14 |    SCLK | ALT0 | 0 | 23 || 24 | 1 | OUT  | CE0     | 10  | 8   |
 |     |     |      0v |      |   | 25 || 26 | 1 | OUT  | CE1     | 11  | 7   |
 |   0 |  30 |   SDA.0 |   IN | 1 | 27 || 28 | 1 | IN   | SCL.0   | 31  | 1   |
 |   5 |  21 | GPIO.21 |   IN | 1 | 29 || 30 |   |      | 0v      |     |     |
 |   6 |  22 | GPIO.22 |   IN | 1 | 31 || 32 | 0 | IN   | GPIO.26 | 26  | 12  |
 |  13 |  23 | GPIO.23 |   IN | 0 | 33 || 34 |   |      | 0v      |     |     |
 |  19 |  24 | GPIO.24 |   IN | 0 | 35 || 36 | 0 | IN   | GPIO.27 | 27  | 16  |
 |  26 |  25 | GPIO.25 |   IN | 0 | 37 || 38 | 0 | IN   | GPIO.28 | 28  | 20  |
 |     |     |      0v |      |   | 39 || 40 | 0 | IN   | GPIO.29 | 29  | 21  |
 +-----+-----+---------+------+---+----++----+---+------+---------+-----+-----+
 | BCM | wPi |   Name  | Mode | V | Physical | V | Mode | Name    | wPi | BCM |
 +-----+-----+---------+------+---+---Pi 4B--+---+------+---------+-----+-----+

(NB. whilst the above was dumped from a P4B a P0 has the same layout etc.)
Trev.

[fruitoftheloom]

Hi guys. Please help!

Need help with GPIO. I have 21 sensors connected to the RP Zero W and I’m not sure which GPIO is best for which sensor.

I have:
- 7 thermistors
- 5 Ammeter
- 4 pcs 5/110VAC really
- 3 buttons (open / close)
- 1 pressure sensor
- 1 wet sensor.

Thank you in advance!

https://pinout.xyz/

[boyoh]

Hi guys. Please help!

Need help with GPIO. I have 21 sensors connected to the RP Zero W and I’m not sure which GPIO is best for which sensor.

I have:
- 7 thermistors
- 5 Ammeter
- 4 pcs 5/110VAC really
- 3 buttons (open / close)
- 1 pressure sensor
- 1 wet sensor.

Thank you in advance!

Before you go any further you must learn the
Difference between Digital electronics and
Analogue electronics, So a course in basic
Electronics is a must for you then you will know
How to interface with the Pi GPIOs
Regards BoyOh

[MShemet]

Thank you for your replay. Temperature sensors we’ve got is digital. The only analog sensor is ammeter and we already have an analog to digital converter.
The question, is there any difference in using different gpio or they are all can be used at any digital sensor.
Thank you.

[hippy]

The question, is there any difference in using different gpio or they are all can be used at any digital sensor.

GPIO2 (SDA1) and GPIO3 (SCL1) have 1K8 pull-ups to 3V3; the others do not. In the majority of cases this should have little effect on digital interfacing but it would be recommended to reserve the I2C pins for I2C interfacing. The same would be true for those pins which support UART and SPI use.

[FTrevorGowen]

The question, is there any difference in using different gpio or they are all can be used at any digital sensor.

GPIO2 (SDA1) and GPIO3 (SCL1) have 1K8 pull-ups to 3V3; the others do not. In the majority of cases this should have little effect on digital interfacing but it would be recommended to reserve the I2C pins for I2C interfacing. The same would be true for those pins which support UART and SPI use.

+1 and to be sure that the sensors use 3.3V logic levels ...
Trev.