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palcal

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Joined: 12/10/2011
Location: Australia
Posts: 1986

Posted: 12:10am 25 Jan 2025

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I changed from HTU21D to AHT10 and modified my code accordingly. The AHT10 won't work,
I checked to make sure I had the correct address &H38 and found while searching that people have had trouble with AHT10 on the same bus as another device. I also have a BMP280 pressure sensor on the bus, address $H40.
Anyone had success with the AHT10 on the same bus as another device.

"It is better to be ignorant and ask a stupid question than to be plain Stupid and not ask at all"

palcal

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Joined: 12/10/2011
Location: Australia
Posts: 1986

Posted: 01:08am 25 Jan 2025

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Just found this....

Quote While technically possible to put an AHT10 on the same I2C bus as another device, it is strongly discouraged as the AHT10 can often disrupt communication on the bus due to its unique communication protocol, making it preferable to use the AHT10 on a separate I2C bus if you need to connect multiple devices; essentially, it's best to use the AHT10 alone on its dedicated I2C bus to avoid potential issues with other devices on the same bus.

Looks like I will have to get some more HTU21D
Edited 2025-01-25 11:10 by palcal

"It is better to be ignorant and ask a stupid question than to be plain Stupid and not ask at all"

phil99

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Joined: 11/02/2018
Location: Australia
Posts: 2605

Posted: 01:12am 25 Jan 2025

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Have had no issue with AHT10 sharing System I2C with DS3231 RTC, 24C32 EEPROM and VL53LOX laser distance device at the same time. Works with all PicoMite firmware.

'AHT10 on System I2C

Dim Float humid, temp
Const AHaddr = &H38 ' AHT10 I2C address
I2C write AHaddr, 0, 3, 172, 51, 0 'trigger first AHT10 measurement to refresh data
Pause 45 'wait for data

Do
T% = timer + 999
AHT10
Print "Temp ";temp;"`C","Humidity ";humid;"%"
Do : Loop Until timer > T%
Loop

Sub AHT10
I2C read AHaddr,1,5,dat() 'read first 5 data bytes - last one not needed.
humid = Cint(dat(1) / 2.56)
temp = Cint((((dat(3) And 15) << 8) + dat(4)) / 2.048 - 500) / 10
I2C write AHaddr, 0, 3, 172, 51, 0 'trigger measurement for next read
End Sub

Edit
The AHT10 address can also be &H39 if a link is bridged. This will find it.

'Find address
I2C write &h38, 0, 1, 0 ' write zero to that adress
If MM.I2C=0 Then ' check for errors
AHaddr = &H38
Else
AHaddr = &H39
EndIf
Print ;" AHT10 address ";Hex$(addr,2);" Hex"

You can run this as is or add it to the setup area of the program above.
Edited 2025-01-25 12:09 by phil99

Footnote added 2025-01-25 12:14 by phil99
Correction, change last line to:-
Print ;" AHT10 address ";Hex$(AHaddr,2);" Hex"

palcal

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Posts: 1986

Posted: 02:06am 25 Jan 2025

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I'm using MX170, would that make a difference.
I'll try it again with your code.
Thanks Phil.

"It is better to be ignorant and ask a stupid question than to be plain Stupid and not ask at all"

phil99

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Location: Australia
Posts: 2605

Posted: 04:34am 25 Jan 2025

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Adapted to PIC32MX170 MM2.
Comment VL53LOX out if you don't have it.

'25/01/2025
'MM2 v5.05.05
'Read AHT10, DS3231 and VL53LOX using I2C
RTC GETTIME : Print Date$, Time$
'pin 17 = I2C clock, Pin 18 = I2C data
I2C OPEN 100, 100, PU
Dim Integer dat(4), dst(1), dist
Dim Float humid, temp, Trtc
Const VLaddr=&H29, AHaddr = &H38 'VL53LOX & AHT10 device addresses
I2C write VLaddr,0,2,0,1 'trigger first VL53LOX measurement
I2C write AHaddr, 0, 3, 172, 51, 0 'trigger first AHT10 measurement

Print "rel. humidity temp distance"
Pause 75 'wait for data

Sub AHT10
I2C read AHaddr, 1, 5, dat() 'read first 5 data bytes - last one not needed.
humid = Cint(dat(1) * 0.390625)
temp = Cint((((dat(3) And 15) << 8) + dat(4)) * 0.48828125 - 500) * 0.1

I2C write AHaddr, 0, 3, 172, 51, 0 'trigger measurement for next read
End Sub

Sub VL53LOX
I2C write VLaddr,1,1,30
I2C read VLaddr,0,2,dst()
dist = (dst(0)<<8) + dst(1)

I2C write VLaddr,0,2,0,1 'trigger measurement for next read
End Sub

Sub DS3231 'read DS3231 RTC temp, if installed
Local integer Tdeg, Tdec
On Error skip 3 : RTC GetReg 17,Tdeg : RTC GetReg 18,Tdec
Trtc = 0.1 * Cint((Tdeg + Tdec / 256)*10) And &hFFF)
End Sub

Do
AHT10
DS3231
VL53LOX 'Comment this out if you don't have it
Print humid;" %",, temp;" C",, "RTC Temp ";Trtc;" C",, dist" mm"
Pause 2000 ' read every 2S
Loop

End

> RUN
25-01-2025 15:33:49
rel. humidity temp distance
52 % 23.2 C RTC Temp 23.3 C 89 mm
52 % 23.3 C RTC Temp 23.3 C 91 mm
52 % 23.2 C RTC Temp 23.3 C 88 mm
52 % 23.2 C RTC Temp 23.3 C 89 mm
52 % 23.2 C RTC Temp 23.3 C 88 mm
52 % 23.2 C RTC Temp 23.3 C 88 mm
>

Quote ... AHT10 on the same I2C bus as another device, it is strongly discouraged .... due to its unique communication protocol

I don't understand this bit. Its communication appears to be exactly the same as any other I2C device.

The program above uses standard MMBasic commands in the standard manner. I haven't included the 24C32 EEPROM in the program but it also works with the AHT10 on the same bus at both 100kHz and 400kHz.
Edited 2025-01-25 15:27 by phil99

palcal

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Posted: 05:21am 25 Jan 2025

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Thanks for that Phil. Will try tomorrow.

"It is better to be ignorant and ask a stupid question than to be plain Stupid and not ask at all"

scruss
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Joined: 20/09/2021
Location: Canada
Posts: 91

Posted: 01:47am 26 Jan 2025

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All the AHT sensors I have used are very well-behaved

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