ItsyBitsy M0 Express & AD5254 Digital POT

[Freehawk]

I don't know for sure this is the right place to ask this question
I not, lead me into the right direction

I try to make digital pot work with Itsybitsy.
This is the datasheet of the AD5254

https://www.analog.com/media/en/technical-documentation/data-sheets/AD5253_5254.pdf​

I based myself on the following document https://learn.adafruit.com/circuitpython-basics-i2c-and-spi/i2c-devices
I can scan the devices (1 with adres 0x2c) (that seems correct)
But i can't find out how to set pot 1 to a value

AD5254 connections

• pin 5 (wp) to VCC
• pin 9 (SDA) to SDA on itsibtsy (with 2.2k pull up resistor to 5v)
• pin10 to GND,
• pin 14 (scl) to SCL (with 2.2k pull up resistor to 5v)
• pin 15 to GND,
• pin 20 to VCC, (5v)
• pin 4 (AD0) do D10 itsibisy (this to be able to set AD0=0)
• pin 16 (AD1) to D11 itsibisy (this to be able to set AD1=0) just to be sure of the slave adress

This is the code i use

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Code C - [expand]
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import busio
import board
from digitalio import DigitalInOut, Direction, Pull
i2c = busio.I2C(board.SCL, board.SDA)
i2c.unlock()
ad1 = DigitalInOut(board.D11)
ad2 = DigitalInOut(board.D10)
ad1.switch_to_output(False)     # Zet AD1 op 0
ad2.switch_to_output(False)     #     AD0
 
while not i2c.try_lock():
    pass
list = [(x) for x in i2c.scan()]
hexlist=[hex(x) for x in list]
 
print('device-list : ', list, hexlist)
 
buf = bytearray(2)
 
i2c.readfrom_into(list[0], buf)
print(buf)
i2c.writeto(list[0], b'0x0', stop=False)
i2c.readfrom_into(list[0], buf)
print('1 :', buf)
i2c.writeto(list[0], b'0x10', stop=True)
i2c.unlock()

---

I get this result in serial window

device-list : [44] ['0x2c']
bytearray(b'\xff\xff')
1 : bytearray(b'\xff\xff')

Anyone any ideas? Please help me out

 

[KlausST]

Hi,

pin 4 (AD0) do D10 itsibisy (this to be able to set AD0=0)
pin 16 (AD1) to D11 itsibisy (this to be able to set AD1=0) just to be sure of the slave adress

I recommend to hard wire them to VCC / GND.

****
In the datasheet you find the examples on how to access the digital POT. look at figures 23 down to figure34.
I cant find out from your code, nor do I find it in your description what exactly you want to do and which scheme you use.

I can´t find which POT you want to acces.
I can´t find what value you want to send.
--> Please explain.

Klaus

 

[Freehawk]

Hi,

I just want to set all pots to a certain value.

Starting with pot 1

I know there are examples in the datasheet
But i don't seem to get them work

 

[KlausST]

Hi,

I know there are examples in the datasheet
But i don't seem to get them work

Show how you tried it.

Klaus