I2C slave mode doesn't work for UnitV Stick
jani last edited by jani
Any ideas how to establish a I2C connection with the M5Stack UnitV as I2C.Slave?
- M5Stack UnitV = I2C Slave
- ESP8266 = I2C Master + Wifi
Setting up the UnitV Stick as a I2C slave is failing. I'm connecting a ESP8266 with ports 34,35 of the UnitV and a 4,7kO Pull-Up resistor.
The scan from the ESP8266 master is successful, but any read
or writeoperation fails with a timeout message. The connection to other I2C devices is successful, when the UnitV is removed from the bus.
UPDATE: Any write operation - before a read - is successful. After the first read, the bus is blocked.
import time from machine import I2C I2C_SLAVE_ADDR = 0x3a count=0 def i2c_on_receive (data): print ("on_receive:", data) def i2c_on_transmit (): count = count + 1 print ("on_transmit, send:", count) return count def i2c_on_event (event): print ("on_event:", event) print ("starting i2c") i2c = I2C(I2C.I2C1, mode = I2C.MODE_SLAVE, scl=34, sda=35, freq = 400000, addr = I2C_SLAVE_ADDR, addr_size = 7, on_receive = i2c_on_receive, on_transmit = i2c_on_transmit, on_event = i2c_on_event) while True: time.sleep(20)
ESP8266 Micropython Code:
from machine import Pin, I2C i2c = I2C(scl=Pin(12), sda=Pin(13), freq=400000) i2c.scan() # returns  i2c.writeto(0x3a,'test') # success, write 4 bytes to slave with address 0x3a result = i2c.readfrom(0x3a, 4) # fails with Timeout print(q)
- Code Cleanup (remove ws2812 reference), add esp8266 code
i2c.deinit()? why you add deinit? that mean is close the I2C bus
jani last edited by
@m5stack The deinit() is just called at the end for cleanup. I2C should work in the endless loop "while True: time.sleep(20)"
Why not just import the neopixel module if you are just driving some ws2812 rgb leds?
jani last edited by
I want create snapshots with the UnitV via WIFI. The ws2812 import is only to show the status of the camera.
UnitV = I2C Slave
ESP8266 = I2C Master + Wifi
I2C problem seems from the maixpy. maybe you could commit a issues to maixpy github
TakekazuKATO last edited by
Is this problem already solved?
It seems to be a mistake in the sample program.
Although, the variable 'count' in the function i2c_transmit() should be global, it is interpreted as local.
I modified the function i2c_on_transmit() as follows:
def i2c_on_transmit (): global count count = count + 1 print ("on_transmit, send:", count) return count
Then, it worked well.