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Control GUI - Error during read servo position
Hi guys,
I am experiencing the following error when read_ServoPos method is called (located within controlGUI.py file):
INFO: Connecting to PiArm on Port /dev/ttyS0 & baudrate 115200..
INFO: PiArm is Initialized
DEBUG: write: b'UU\x01\x04\x1f\x01\xda'
DEBUG: notification: Serial Device Connected
DEBUG: write: b'UU\x01\x03\x1c\xdf'
DEBUG: response: [b'U', b'U', b'\x7f', b'~', b'\\', b'\x00']
Exception in Tkinter callback
Traceback (most recent call last):
File "/usr/lib/python3.7/tkinter/__init__.py", line 1705, in __call__
return self.func(*args)
File "/home/pi/PiArm/controlGUI.py", line 279, in read_ServoPos
pos = int.from_bytes(response[5]+response[6], byteorder='little')
IndexError: list index out of range
The code is in accordance with Servo Communication Protocol.pdf specification. Based on DEBUG logs, received array has only 6 items, so with zero-indexed array, there is no response[6] element.
When I "workaround" the error with pos = int.from_bytes(response[4], byteorder='little') on line 279, the console output is as follows:
INFO: Connecting to PiArm on Port /dev/ttyS0 & baudrate 115200..
INFO: PiArm is Initialized
DEBUG: write: b'UU\x01\x03\x1c\xdf'
DEBUG: response: [b'U', b'U', b'\x7f', b'~', b'\\', b'\x00']
DEBUG: write: b'UU\x02\x03\x1c\xde'
DEBUG: response: [b'U', b'U', b'\xbf', b'\xc7', b'C']
DEBUG: write: b'UU\x03\x03\x1c\xdd'
DEBUG: response: [b'U', b'U', b'~', b'~', b'\\', b'\x04']
DEBUG: write: b'UU\x04\x03\x1c\xdc'
DEBUG: response: [b'U', b'U', b'_', b'\xc7', b'G']
DEBUG: write: b'UU\x05\x03\x1c\xdb'
DEBUG: response: [b'U', b'U', b'}', b'~', b'\\', b'\x02']
DEBUG: write: b'UU\x06\x03\x1c\xda'
DEBUG: response: [b'U', b'U', b'\xbe', b'\xc7', b'K']
Please note that responses from servos 1,3,5 have 6 items while responses from servos 2,4,6 have 5 items only. When I move with arm manually and read the values again, they remain the same. Moreover, writes to servos return no error, but no servo is moved.
My setup is as follows:
- Raspberry Pi 4 8GB, Raspberry Pi OS (32-bit) with desktop and recommended software
- PiArm Basic Kit (purchased recently)
- Servo Shield connected via GPIO
- Arm connected via JST connector type 1 (number 14 in your lesson 1); number 7 has the same behavior
- LED on servos are blinking a 7 color sequence + turned off (does it mean something?)
- powered by included AC adapter
- servos are daisy-chained - wire from servo below going into left socket, then wire from right socket to next servo up; as described in MagPi review; wiring based on you tutorial where motors 3 and 2 are wired differently makes no change in behavior
Where else should I look for the error reason? Is it something wrong with the shield? Is it Raspberry Pi 4?
Please help.
Regards, Jan
I am solving the issue with support via other channel. I'll put here the solution once it'll be known...
For now, the only working solution is connecting the shield via USB - everything works as expected. Except the buzzer beeps for some unknown reason, but it can be turned off by removing jumper (marked by number 1 in lesson 1)
I'll post updates, when new information will come...