Hi people, I need your help. Your input is highly appreciated!
I've been trying to contact the author of an Arduino Indoor Garden Project almost 2 weeks ago, unfortunately without success, like others. It's a very interesting project with detailed description of how to setup arduino-operated sensors and actuators to make a fully automated indoor gardening system controlling soil humidity, air humidity and lighting. I'm trying to work out a modified version of this project for learning purpose and I'm wondering whether the electronics schematic might need some further improvements. The schematic can be found here: arduino indoor schematic
1: In the Indoor Garden Schematic I see that the IRF540 power mosfet for pump control is connected in a different way to the VPN port as compared to the other 2 (fan&light brightness). Is that correct or should I change it?
2: I've seen other schematics that use a voltage divider (1k /2k resistors) between the TX pin of the arduino nano and the bluetooth hc-06 module RXD pin. Such voltage divider wiring has been used between ESP-RXD pin (nano) and RXD pin from the ESP-01 Module but not between TX pin nano and RXD pin HC-06. Is that correct? Won't it damage the HC-06 long-term?
3: Regarding the RXD and TXD connections I see that ESP-TXD (nano) wires to TXD (ESP-01) whereas TXD (nano) wires to RXD (HC-06). I'm not familiar with RXD TXD communication protocols. Why this TXD-TXD vs. TXD-RXD difference? Is that naming correct as well?
4: What's the correct placement of fuses? Shouldn't it be on the +12V positive lead instead of Ground?
Any tips, suggestions? Thanks!
Lucas
I can help you with Q4.
You always put some sort of cutout between your circuit and the power source so if anything goes wrong anywhere the power is disconnected and we usually put this in the posative lead as most circuits have a common ground.
As you branch out your power to other devices is can help to put other fuses in to protect those items.
E.g. the Arduino has an onboard fuse to protect its self.
The fuse at the powersource is there in the event that ANYTHING in your circuit (wires included) has a catastrophic failure.
A fuse in the negative lead will do the same thing but as so many things have 'Common Ground' connecting another device could accidently create another path to ground bypassin your fuse
Remember the main fuse must be of high enough value to supply current to all the devices conntcted.
Daz
but not between TX pin nano and RXD pin HC-06. Is that correct?
No. Use the divider. It is always a good idea, except if you have a 3.3v Arduino
3: Regarding the RXD and TXD connections I see that ESP-TXD (nano) wires to TXD (ESP-01) whereas TXD (nano) wires to RXD (HC-06). I'm not familiar with RXD TXD communication protocols. Why this TXD-TXD vs. TXD-RXD difference? Is that naming correct as well
Transmitters transmit to receivers that receive. Tx>Rx and Rx<Tx.
Hi Nick_Pyner,
Thank you very much for your reply. This is very helpful. Just to be sure I understand you correctly:
1:So I'll have to use the devider between the Tx pin of arduino nano, which runs on 5 V and Rx pin of HC-06 which runs on 3.3 V?
2: So the naming is not correct in the scheme? ESP-TXD (arduino nano) should wire to a port named RXD on the ESP-01 device?
Kind regards,
Lucas Herfst 
Hi DAZ,
Thank you very much for your reply. My understanding about placement of the fuses seems to be correct. Bypassing the fuse is not such a good idea. I'll take care to use sufficient value for the fuse since high-power LEDs, perhaps in several strings may consume quite a bit of power.
Kind regards,
Lucas Herfst
herfst_lj:
1:So I'll have to use the devider between the Tx pin of arduino nano, which runs on 5 V and Rx pin of HC-06 which runs on 3.3 V?
Yes, it is good practice, but I have never actually heard of a fatal result if you don't do it. You might find the following background notes useful. There is a wiring diagram!
http://homepages.ihug.com.au/~npyner/Arduino/GUIDE_2BT.pdf
http://homepages.ihug.com.au/~npyner/Arduino/BT_2_WAY.ino
ESP-TXD (arduino nano)
I think this is meaningless. See last line in reply #2.
Hi Nick,
Thanks a lot, also for your quite extensive information in the PDF and arduino code!
Very confusing schematic. I just can't figure out what VPP and VPN are supposed to do.
The MOSFETS appear to be all connected in the same way. Dunno why he's using the IRF540 rather than the IRL540, as the latter can actually be switched with 5V, the former not.
That thing is also using the cheapest and crappiest sensors around, particularly the DHT11 and that resistive soil sensor (the only way to make that kind of sensor last longer than a month or two is by completely disconnecting the power when not taking readings, and taking infrequent readings).
Can I share some more radical ideas on the design?
Get rid of the Bluetooth. It already has WiFi and WiFi is better. You can view/adjust from anywhere in the world, not just the same room.
Get rid of the Nano and esp-01. Replace with Wemos Mini or similar. Simplifies the design and gives you a far more powerful Arduino to play with.
Get rid of the dht11. Replace with sht21. Much more accurate and can share i2c bus with the bh1750 sensor.
more modernization :
get rid of the soil sensor. use a capacitive sensor.
CHIRP
wvmarle:
Very confusing schematic. I just can't figure out what VPP and VPN are supposed to do.
The MOSFETS appear to be all connected in the same way. Dunno why he's using the IRF540 rather than the IRL540, as the latter can actually be switched with 5V, the former not.
That thing is also using the cheapest and crappiest sensors around, particularly the DHT11 and that resistive soil sensor (the only way to make that kind of sensor last longer than a month or two is by completely disconnecting the power when not taking readings, and taking infrequent readings).
Thank you wvmarle. Perhaps it's better to have a bit more decent components on it.
Regarding the MOSFETS: They are correctly connected in the schematic?
PaulRB:
Can I share some more radical ideas on the design?
Get rid of the Bluetooth. It already has WiFi and WiFi is better. You can view/adjust from anywhere in the world, not just the same room.
Get rid of the Nano and esp-01. Replace with Wemos Mini or similar. Simplifies the design and gives you a far more powerful Arduino to play with.
Get rid of the dht11. Replace with sht21. Much more accurate and can share i2c bus with the bh1750 sensor.
Thanks Paul for your suggestions. I have to do some redesign I guess
dave-in-nj:
more modernization :
get rid of the soil sensor. use a capacitive sensor.
CHIRP
Well that's a nice sensor indeed. But I have to reconsider my budget..
IMHO
the capacitive soil one linked offers good optins. I2C, or for lots more $$ RS484
for a lot less money, Aliexpress : analog soil sensor
you have to use an Analog pin to read this one.
dave-in-nj:
for a lot less money, Aliexpress : analog soil sensor
You just have to waterproof it The electronics don't look like they're protected at all.
wvmarle:
You just have to waterproof it The electronics don't look like they're protected at all.
OK wvmarle, That's a decent price for an analog soil sensor. I'll waterproof the electronics.