HC-SR504 on esp8266
Posted: Thu Nov 10, 2016 12:26 am
Hi list,
I have been running an ultrasonic sensor on a raspberry pi for a while, with quite some good results.
I wanted to port this on an esp8266 and, it looks like the result are a bit less accurate than on the pi.
Here is the graphs usage of each one :
pi :
esp8266 :
The line is quite smoother on the pi.
Here is the code i use on the esp8266 to get the values :
I suspect that the tick is less reliable on the esp8266 than on the pi. For example, in an other project, using a timer of 90000 milliseconds yield in a run of 82 seconds.
Any idea on how the code could be getting better result out of this sensor on esp8266?
Cheers!
I have been running an ultrasonic sensor on a raspberry pi for a while, with quite some good results.
I wanted to port this on an esp8266 and, it looks like the result are a bit less accurate than on the pi.
Here is the graphs usage of each one :
pi :
- pi_hc-sr504.png (18.99 KiB) Viewed 6635 times
esp8266 :
- esp8266_hc-sr504.png (19.69 KiB) Viewed 6635 times
The line is quite smoother on the pi.
Here is the code i use on the esp8266 to get the values :
Code: Select all
import time
import machine
trigger_pin=5
echo_pin=4
trigger=machine.Pin(trigger_pin, machine.Pin.OUT)
echo=machine.Pin(echo_pin, machine.Pin.IN)
def get_distance():
trigger.low()
time.sleep_us(5)
trigger.high()
time.sleep_us(10)
trigger.low()
while echo.value()==0:
start=time.ticks_us()
while echo.value()==1:
delta=time.ticks_diff(time.ticks_us(), start)
distance=(delta/2)/29
return distance
I suspect that the tick is less reliable on the esp8266 than on the pi. For example, in an other project, using a timer of 90000 milliseconds yield in a run of 82 seconds.
Any idea on how the code could be getting better result out of this sensor on esp8266?
Cheers!