ESP8266 Community Forum

- Mon Jan 25, 2016 4:33 pm #39686 another issue...
i see in the datasheet that the pins are all activated by a LOW pulse. In this case , considering that my pulse are HIGH , i need to use a NPN per channel?

thanks

- Wed Jan 27, 2016 11:05 am #39827 Ok, the winner is : 74HC279

It seems perfect for my needs.
Testing it yesterday i undestand another problem of my project. Considering that i'm using bistable electrovalve , if one of these are opened during the job the ESP dies ... the valve remains opened .... and my garden will be awash!
So i need a system to send to the relay the command to close them. I'm thinking about it:
one transistor connected with gpio15 (that is HIGH every time to enable the l293) , when the esp dies , the pin is in pull-down so the pin will be LOW (is it right?) and activates the transistor. The transistor connect the 4 pins of the l293d that sends the reset command to the relays (-+ to the relays ... powered by the battery). If the valve is opened , will be closed; if closed ... remains closed.
Only problem could be the reset during the boot of the esp , considering that gpio15 is in low, but during the boot, it could be a good feature too.

In your opinion , it is a reasonable solution? The transistor must be a PNP?
Maybe better something else (555?) , but what else?
Thanks

- Sun Feb 07, 2016 8:31 am #40614 [quote="martinayotte"]Yes, GPIO15 will be good for those EN pins.
No series resistors, but still GPIO15 pulldown resistor, something like 4K7 or 10K to GND.
So, in your code, digitalWrite(MOTOR_ENABLE, 1) will bring the EN pins to HIGH.[/quoten

Hi mister ..
maybe i need your help . Do you rememmber my solution to enable the l293d with gpio15? On the start the gpio15 is low, so i haven't accidental start of the valve. Than i put high the gpio15 , and it enables the Hbridges.
The Hbridges are two, and they are enabled by the same gpio15. The problem is that if i put high gpio15, they run for only 10 secs ... than i have a sort of blinking for 1 minute, and than the switch off. The esp07 is burning during this job !!!
What does it means? Maybe the esp07 has not enough mA for both? But I have the problem with only one Hbridge too ..... and ... with only a led connected to the gpio15. Where i need to search the problem?

to test my board a put enable l293 on the start connecting them on the v+. Of course i have a switch on of the valve during the boot, but it is to test them! Another problem is the first hBridge. It seems ALWAYS up, it ALWAYS supplies power to the valve. It is drived by the gpio 16,14,12,13 They are free .. no pulldown and pull up on them.
On the other side i have the second hBridge perfectly working. It is drived by gpio : 4, 5, 2,0 (2 pullup, 0 pullup).

Maybe it is the board design?? with the link you can find it (it is ona of my first board, so probably it has some errors).
Thanks for your help in advance!

Mirko

design layout: https://easyeda.com/editor#id=CNkQ82e8qH

- Sun Feb 07, 2016 8:35 am #40615

Yes, GPIO15 will be good for those EN pins.
No series resistors, but still GPIO15 pulldown resistor, something like 4K7 or 10K to GND.
So, in your code, digitalWrite(MOTOR_ENABLE, 1) will bring the EN pins to HIGH.[/quoten

Hi mister ..
maybe i need your help . Do you rememmber my solution to enable the l293d with gpio15? On the start the gpio15 is low, so i haven't accidental start of the valve. Than i put high the gpio15 , and it enables the Hbridges.
The Hbridges are two, and they are enabled by the same gpio15. The problem is that if i put high gpio15, they run for only 10 secs ... than i have a sort of blinking for 1 minute, and than the switch off. The esp07 is burning during this job !!!
What does it means? Maybe the esp07 has not enough mA for both? But I have the problem with only one Hbridge too ..... and ... with only a led connected to the gpio15. Where i need to search the problem?

to test my board a put enable l293 on the start connecting them on the v+. Of course i have a switch on of the valve during the boot, but it is to test them! Another problem is the first hBridge. It seems ALWAYS up, it ALWAYS supplies power to the valve. It is drived by the gpio 16,14,12,13 They are free .. no pulldown and pull up on them.
On the other side i have the second hBridge perfectly working. It is drived by gpio : 4, 5, 2,0 (2 pullup, 0 pullup).

Maybe it is the board design?? with the link you can find it (it is ona of my first board, so probably it has some errors).
Thanks for your help in advance!

Mirko

design layout: https://easyeda.com/editor#id=CNkQ82e8qH

if you look the board , up and down board are the same! It is only for the printing