Vehicle onboard double-control-chip system and auxiliary control chip program update method therefor

The present invention discloses an auxiliary control chip program update method for a vehicle onboard double-control-chip system. The method comprises: connecting an IO control pin of a main control chip to a reset pin of an auxiliary MCU; setting a communication ID identification number for communication between an upper computer and a lower computer; defining a ROM area where the BOOT and the program of the auxiliary control chip are located; downloading a to-be-updated program to the corresponding ROM area; integrating transfer functions of a CAN communication tool and an SPI communication tool of the main control chip into ESP system functions; connecting the upper computer with a whole vehicle CAN network by using the CAN communication tool; ensuring that a session response between the upper computer and the lower computer and a key checking mechanism meet a whole vehicle CAN network standard; an auxiliary control chip program file being a standard S19 format file; and performing, by the main control chi