CPFA
write_chan(dev, CPFA, 0, 0);
write_chan(dev, CPFA, 1, 0);
write_chan(dev, CPFA, 3, 0);
offset = read_chan(dev, CPFA, 0);
write_chan(dev, CPFA, i, 0);
write_reg(dev, CPFA, i, 0);
offset = read_reg(dev, CPFA, 0);
write_reg(dev, CPFA, i, 0);