Hardware interface circuit between CH375 and single chip microcomputer

The H375 bus interface chip is produced by Nanjing Qinheng Company. This chip is responsible for processing the USB protocol. It has an 8-bit data bus and read, write, chip select control lines and interrupt output. It can be easily connected to the system bus of a controller such as a single-chip microcomputer, and supports two modes: USB-HOST and USB-DEVICE (SLAVE). The host endpoint input and output buffers are 64 bytes each, supporting control transmission, bulk transmission, and interrupt transmission of USB devices. It has a built-in protocol processor for control transmission and a dedicated communication protocol for processing mass storage devices. It supports 5V and 3.3V power supply voltages (CH375A is powered by 5V, and CH375V is powered by 3.3V), and supports low power consumption mode. It uses SOP-28 lead-free package.

The hardware interface diagram of CH375 and AT89S52 is shown below. D7~DO of CH375 chip is connected to the data line of microcontroller. RD and WR pins can be connected to the read strobe output pin and write strobe output pin of microcontroller respectively. CS pin is driven by address decoding circuit and is used for device selection when microcontroller has multiple peripheral devices. The interrupt request output by INT pin is low level effective and can be connected to interrupt input pin or ordinary I/0 pin of microcontroller. Microcontroller can use interrupt mode or query mode to know interrupt request.