Closed H60gh closed 6 years ago
Hi there @H60gh,
If alpha.ping()
is returning False
, then the device is connected properly, but is not returning the correct value when the SPI command is sent. Have you tried any other commands? With Python2.7, try using the OPCN2
class rather than the OPC
class. Also, which version of the library are you using?
Hi @dhhagan I have same problem in Pytho 2.7 (Warning: Data Transfer was incomplete). Also I test other commands likes "read_info_string", only blank lines are printed!
My using libraries are: py-opc (1.4.1) spidev (3.0)
In addition, I am using GPIO pins.
Ok. I add one minute sleep and it works. But all values are zero!!
Hmm. Have you tried multiple readings? How are you wiring up the device? Can you post an image or wiring diagram?
Thank you Hagan. After multiple reading, I receive PM1, PM2.5 and PM10 values.
No problem. Depending on the unit you purchased, it may not physically be installed. I think Alphasense stopped adding them a couple of years ago unless you special order it (not sure why...). I add an external RHT sensor (SHT31 by Sensirion).
I connect a PM2.5 sensor into Reaspberry pi using SPI. Then I follow the example in Python 3.4.2, but it seems "alpha/alphasense" variable does not work well and alpha.ping() returns "False". As I test, spidev works well. I switch into Python 2.7.9 ("alpha = opc.OPCN2(spi)" is modified to "alpha = opc.OPC(spi))" and now alpha is an unknown variable. How can I solve this problem?
I should mentioned that alpha.on() and alpha.off() functions work well, but it seems something is wrong during data transfer between the sensor and the Rpi.