I'm trying to get data through my serial port from a CMUcam.
This gizmo tracks a color and returns a packet of data. The
packet has nine data points (well, really eight since the first
point is just a packet header) separated by spaces as follows: M
xxx xxx xxx xxx xxx xxx xxx xxx
Here is the code I am using (python v24):
import serial
ser=serial.Serial('com1',baudrate=115200, bytesize=8,
parity='N', stopbits=1,xonxoff=0, timeout=1)
ser.write("PM 1") #This sets the CMUcam to poll mode
for i in range(0,100,1):
ser.write("TC 016 240 100 240 016 240\r\n")
reading = ser.read(40)
print reading
components = reading.split()
print components
ser.close
Here is an example output:
M 37 79 3 4 59 124 86 25
['59', '123', '87', '25', 'M', '37', '79', '3', '4', '59',
'124', '86', '25', 'M
']
M 38 77 3 2 59 124 86 25
['39', '85', '26', 'M', '38', '77', '3', '2', '59', '124', '86',
'25', 'M', '38'
, '7']
My problem is that I am trying to get each data point of the
packet into a separate variable. Ordinarily, this would be easy,
as I would just parse the packet, read the array and assign each
element to a variable eg. mx = components[1]. However, that
doesn't work here because the original packet and the array that
I got from using the split() method are different. If I were to
try read the array created in the first example output, mx would
be 123 instead of 37 like it is in the packet. In the second
example, the array is 85 while the packet is 38.
As near as I can figure out, pyserial is reading a stream of
data and helpfully rearranging it so that it fits the original
packet format M xxx xxx xxx xxx xxx xxx xxx xxx. I would have
thought the split() method that I used on original packet (ie
the "reading" variable) would have just returned an array with
nine elements like the packet has. This is not the case, and I
am at a loss about how to fix this.
I've searched the archive here and elsewhere with no luck. Any
help REALLY appreciated!
Wolf :)
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