dc_i2c_cmd
dc_i2c_cmd(i2c, last ? II_CMD_GET_NOACK : II_CMD_GET_ACK);
dc_i2c_cmd(i2c, II_CMD_STOP);
dc_i2c_cmd(i2c, first ? II_CMD_START : II_CMD_RESTART);
dc_i2c_cmd(i2c, II_CMD_SEND_ACK);