Which T34/BK7231N pins do I use for a DHT22 sensor?
S1 provides GND and S2 goes to GPIO14 (CPU pin 11); add 3.3 V from VCC to the sensor and remove the on-board pull-up/cap at BC8 [Elektroda, Tilator, post #21095664]
Adding a DHT22 Temperature Sensor to T34/BK7231N for Room Heating Control
TL;DR
- Modified a T34/BK7231N heater controller by adding a DHT22 temperature sensor for room-temperature sensing and relay-based heating on/off control.
- Wired the sensor to the S1/S2 external switch connector: S1 to ground, S2 to GPIO P14/pin 11, removed the sensor’s NC pin, and used jumper power for VCC.
- Removed the pullup resistor and capacitor on P14 near the relay under marking BC8, and flashed without desoldering the CPU by soldering UART to BR4.
- The DHT22 reported correct values immediately; a DHT11 also worked only with divider adjustments.
Hello,
There seems to be multiple different layouts available of this device.
My need was to add a temperature sensor in it to make possible to measure room temperature and use the relay to connect heating on and off.
There is S1 and S2 connectors for external switch. I used those to connect DHT22 sensor. S1 is ground and S2 ic connected to GPIO P14, which is pin11 on the CPU. I just took the NC pin off the sensor. All three other pins are at suitable distance from each other to fit the connector.
There is a pullup resistor and capacitor between this P14 and VCC. I took them both off. They are located near the relay under marking BC8.
Only VCC to the sensor needs to be addeb by jumper.
I did not desolder the CPU to flash it. One UART wire can be soldered to the BR4 resistor at the end near number 4. For the second one I used a big and sharp normal knitting needle from my wifes reserves. I holded it at the plase simply by hand. It's easier to keep it on the right spot if it is sharp enoug.
DHT22 sensor gives right values right away. I did try a DHT11 too and it seems to need some dividers to give correct value.
Here is what it looks like:
Here is configuration:
DHT22 is where originally should be BTN_TGL_ALL to act as external on/off switch.
Related T34 topic (flashing method): https://www.elektroda.com/rtvforum/topic4036975.html
For more info, see: https://www.elektroda.com/rtvforum/find.php?q=T34
Comments
Yes, this is a good idea. With OBK , such modifications are very easy. We've did similiar thing with DHT11 on our YT channel: https://www.youtube.com/watch?v=KEjOPuYd3CE The second modification that... [Read more]
You are right and I'm aware of it. The cap you can see is only there to demonstrate the connection. Final installation needs some glue between the parts. Can you tell me is it possible to read the temperature... [Read more]
I think our OBK channels command should work: http://192.168.0.163/cm?cmnd=channels Please try it out and let me know if it works for you. [Read more]
Thanks. [Read more]
Hello again, There seems to be DS18B20/DS1820 support available now. Thank you again. This was good add on it. I have not tested it yet, but will do it as soon as I have a bit spare time. [Read more]
I'm eager to hear some feedback! Please try and let know. PS: Don't use PowerSave 1 with it. [Read more]
@tilator does your DHT22 give readings still with the latest builds? I don't suppose you ever took a pic of the PCB inside the casing? I'm just curious about my one which doesn't seem to work with OBK... [Read more]
At least version version 1.17.661 works fine. Pictures are available if they anyhow help you. [Read more]
Now I had time to try it, but DS18B20 sensor does not come available. There are at least two different physical configurations to install this sensor. Which one should I use? I installed it by connecting... [Read more]
I've always done it like this: https://obrazki.elektroda.pl/7110850100_1727165493_thumb.jpg seen in my pic here https://www.elektroda.com/rtvforum/viewtopic.php?p=21158431#21158431 [Read more]
I did try that too without good outcome. I have this T34 SOC and I try to use GPIO 11 which is UART TX. Might there be some setting wrong related to that? Added after 5 [hours] 11 [minutes]: Seems... [Read more]
So, to sum up, you are using GPIO 11 which is UART TX and: - DHT22 works there - LED (to blink it, as Rel role or LED role) works as well - but DS18B20 doesn't work? Added after 34 : Maybe you... [Read more]
Yes, and on top of thet GPIO 9 works with DHT22 too but not with DS18B20. How can I find out if it's on? [Read more]
I thought powersave 1 was OK now with DS1820? https://www.elektroda.com/rtvforum/viewtopic.php?p=21190145#21190145 @max4elektroda [Read more]
Can you tell does the driver give sensor enough power by pulling GPIO line up or does it still need other external power and pull up resistor? [Read more]
I took one of those mini relays having BK7231N and connected DS18B20 to it using GBIO 9. Still no temperature reading. If I add sensor usin WEB UI there happens nothing. No loaded driver listed on front... [Read more]
still requires external power afaik so, 3.3v, gpio and ground. 4.7kohm between data and vcc. [Read more]
Thanks. A bit new info: I got some readings from BK7231N device and the tric was to give it a bit higher voltage. 4,75V. Even thogh the values it gove were a bit high somewhere above 33 C while actual... [Read more]
What's this in log: Info:SENSOR:DHT start, pin is 6 Info:SENSOR:DHT checksum failure! it keeps repeting about once every second. [Read more]