Changes

for t in range(10):

data_list.append( data2*t + (data2*t+1<<8) )

# compute the checksum on 32 bits

chk32 = 0

for d in data_list:

chk32 = (chk32 << 1) + d

# return a value wrapped around on 15bits, and truncated to still fit into 15 bits

checksum = (chk32 & 0x7FFF) + ( chk32 >> 15 ) # wrap around to fit into 15 bits