Hello ADA Fruit,
Just got one of your cool USB Power Gauge Mini Kit. Fascinated by TX pin that sends out the Voltage, Current and Power. I would like to hook up this TX pin to my Raspberry Pi but I am little bit not sure about voltage levels 5v or 3v?. Can USB Power Gauge TX pin be directly wired up to the Pi? ( presumably connecting to GPIO15 UART RXD?)
I am guessing that if it's safe to wire up then it's just a hop, skip and jump to be reading those values inside the pi?
any help appreciated, thank you
Tokyo Joe.
USB Power Gauge talking to RPi?
Moderators: adafruit_support_bill, adafruit
Please be positive and constructive with your questions and comments.
- adafruit_support_rick
- Posts: 35092
- Joined: Tue Mar 15, 2011 11:42 am
Re: USB Power Gauge talking to RPi?
TX runs at 5V. You can use a resistive divider to protect your Pi.
Connect a 10Kohm resistor between the TX pin and the Pi GPIO pin, and connect another 10K resistor between the Pi GPIO pin and GND. This will reduce the voltage from the TX pin to 2.5V, which will still be readable by the Pi.
Connect a 10Kohm resistor between the TX pin and the Pi GPIO pin, and connect another 10K resistor between the Pi GPIO pin and GND. This will reduce the voltage from the TX pin to 2.5V, which will still be readable by the Pi.
- thalesvon
- Posts: 5
- Joined: Thu Jun 09, 2016 3:04 pm
Re: USB Power Gauge talking to RPi?
Hello,
did this set up worked for you? I am trying to read the TX pin from the USB power gauge mini kit connected to my PI. I used the resistor divider like described. But what is the format of the data out of the TX pin ? In the meanings of parity ,stop bits , data size ?
did this set up worked for you? I am trying to read the TX pin from the USB power gauge mini kit connected to my PI. I used the resistor divider like described. But what is the format of the data out of the TX pin ? In the meanings of parity ,stop bits , data size ?
- adafruit_support_rick
- Posts: 35092
- Joined: Tue Mar 15, 2011 11:42 am
Re: USB Power Gauge talking to RPi?
8 bits, no parity, 1 stop bit. 9600 baud.
It's a readable string of the voltage, current, and wattage readings
It's a readable string of the voltage, current, and wattage readings
- thalesvon
- Posts: 5
- Joined: Thu Jun 09, 2016 3:04 pm
Re: USB Power Gauge talking to RPi?
Hello,
I used the resistor divider to connect the TX to the RX of the PI (GPIO 15) and GND from the power gauge to GND to the PI and still I get no reading on the PI. How can I test if the TX on the power gauge is working properly ?
I used the resistor divider to connect the TX to the RX of the PI (GPIO 15) and GND from the power gauge to GND to the PI and still I get no reading on the PI. How can I test if the TX on the power gauge is working properly ?
- adafruit_support_rick
- Posts: 35092
- Joined: Tue Mar 15, 2011 11:42 am
Re: USB Power Gauge talking to RPi?
Can you post some pictures of your wiring?
Do you have the console serial port enabled or disabled on the Pi? How are you attempting to read the serial data?
Do you have the console serial port enabled or disabled on the Pi? How are you attempting to read the serial data?
- TokyoJoe
- Posts: 3
- Joined: Sat May 24, 2014 11:05 pm
Re: USB Power Gauge talking to RPi?
hello thalesvon
This page is really useful, it showed me how to connect python to the PI's UART https://electrosome.com/uart-raspberry-pi-python/
Once you know you can talk to you PI's UART you'll be in a better position to debug the next step of getting the PI to talk to the USB power gauge.
happy hacking and post some photos
(And thank you Rick for supporting too :-)
This page is really useful, it showed me how to connect python to the PI's UART https://electrosome.com/uart-raspberry-pi-python/
Once you know you can talk to you PI's UART you'll be in a better position to debug the next step of getting the PI to talk to the USB power gauge.
happy hacking and post some photos
(And thank you Rick for supporting too :-)
- thalesvon
- Posts: 5
- Joined: Thu Jun 09, 2016 3:04 pm
Re: USB Power Gauge talking to RPi?
Hello guys,
sorry for the delay. I didn't have access to the devices during the weekend.
I noticed I am running a newer version of Raspbian on my PI. So my PI doesn't have the inittab file.
This is how the cmdline.txt looks like in my PI:
dwc_otg.lpm_enable=0 console=tty1 root=/dev/mmcblk0p2 rootfstype=ext4 elevator=$
On the /boot/config.txt I changed the field
enable_uart=1
The python code I am running on the PI is:
import serial
ser = serial.Serial(port= "/dev/ttyAMA0",
baudrate = 9600,
parity=serial.PARITY_NONE,
stopbits=serial.STOPBITS_ONE,
bytesize=serial.EIGHTBITS,
timeout=1)
while True:
rcv = ser.readline()
if len(rcv) > 1 :
print rcv
And the code is always stuck on the ser.readline().
Do you guys know what I am doing wrong.
Thanks for the help
sorry for the delay. I didn't have access to the devices during the weekend.
I noticed I am running a newer version of Raspbian on my PI. So my PI doesn't have the inittab file.
This is how the cmdline.txt looks like in my PI:
dwc_otg.lpm_enable=0 console=tty1 root=/dev/mmcblk0p2 rootfstype=ext4 elevator=$
On the /boot/config.txt I changed the field
enable_uart=1
The python code I am running on the PI is:
import serial
ser = serial.Serial(port= "/dev/ttyAMA0",
baudrate = 9600,
parity=serial.PARITY_NONE,
stopbits=serial.STOPBITS_ONE,
bytesize=serial.EIGHTBITS,
timeout=1)
while True:
rcv = ser.readline()
if len(rcv) > 1 :
print rcv
And the code is always stuck on the ser.readline().
Do you guys know what I am doing wrong.
Thanks for the help
- Attachments
-
- That is the setup. The voltage divider is with two 10k resistor and the GND of both devices are common.
- 13411914_1136820629716873_4036461661919720561_o.jpg (248.49 KiB) Viewed 193 times
-
- That is the PI with the orange wire being the RX (GPIO 15) and white being GND
- 13411760_1136820566383546_4412352830134685665_o.jpg (319.96 KiB) Viewed 193 times
- thalesvon
- Posts: 5
- Joined: Thu Jun 09, 2016 3:04 pm
Re: USB Power Gauge talking to RPi?
Hey guys just an update,
I figured out what was going on. I am using the Pi 3 and things changed a little.
On the Pi 3 the UART port at the GPIO header is available at "/dev/ttyS0".
So to access it I added the line to the saved it and rebooted it!
After that I changed the device on the python code and it worked great. I am getting the readings now.
Here is the link that I looked:
https://frillip.com/raspberry-pi-3-uart ... orkaround/
Thank you again
I figured out what was going on. I am using the Pi 3 and things changed a little.
On the Pi 3 the UART port at the GPIO header is available at "/dev/ttyS0".
So to access it I added the line
Code: Select all
core_freq=250
Code: Select all
/boot/config.txt
After that I changed the device on the python code and it worked great. I am getting the readings now.
Here is the link that I looked:
https://frillip.com/raspberry-pi-3-uart ... orkaround/
Thank you again
Please be positive and constructive with your questions and comments.