Abstract: CH371 is a new USB Universal bus interface chip. The chip can use USB protocol do not know of any drivers or firmware or even the circumstances, easily upgrades to the parallel or USB serial interface. This paper describes the main features of the interface chip and pin functions are given CH371 and several other bus interface, application circuit, and gives the CH371 and MCS-51 microcontroller interface program.
CH371 is a USB bus interface chip. The chip has an 8-bit data bus and read, write, chip select control lines and interrupt output can be easily attached to the MCU, DSP, MCU and other controllers of the system bus; in the computer system, the supporting software by CH371 provide clean and simple user interface, making it communicate with the local microcontroller to read and write to the hard disk as a file as simple as that. As CH371 shielded USB communications for all protocols, thus the application layer in the computer controller with local connections to provide end to end. USB protocol do not need to know of any firmware or even in the case of the driver, you can easily parallel port, serial port upgrades to the USB interface.
CH371 The main features are as follows:
shielded the USB protocol, the computer application layer end to end between the local client connections. request a one-way data flow and response of two additional modes of communication and support for pseudo-interrupts. USB configuration process can be done automatically, completely without any treatment for local control. a standard USB1.1 interface, plug and play, D + pins are connected to internal resistance. Built-in 4 endpoints to support USB control transfer, bulk transfer, interrupt transfer.
with a generic Windows driver, which provides device-level interface and application layer interfaces.
8-bit data with a common local bus, 4-wire control can be read strobe, write strobe, chip select input and interrupt output.
takes 16 addresses, you can choose a direct address mode, or multiplexed address mode.
Built-in input and output buffers, can notify the local interrupt controller to transfer data.
Built-in I2C master interface, so the application layer can be directly read and write I2C plug from the device.
In the master mode can provide the input signal line 16 or 12 independent control of the output signal line.
Built-in power-on reset circuit, which provides active-high reset output, and active-low reset output.
includes the optional watchdog circuit Watch-Dog, the controller provides for local control.
has DIP28, SOP28, DIP24, CHIP and other packages.
2 pin function
CH371 pinout shown in Figure 1, Table 1 is the pin functions.
Pin Function Table 1 CH371
24-pin package pin number
Pin No. Pin Name Type Pin Description
2824VCC power supply positive terminal
129GND Power Ground
1411XI input crystal oscillator input with bias resistors
1310XO inverting the output crystal oscillator output
107D + two-way USB D + data line, built-in pull-up resistor control
118D-way USB D-data line
96OFF input is used to close the D + host resistance, high effective, with a drop-down
22151912D7D0 bidirectional 8-bit bidirectional data bus, pull-up, independent control can be directly input and output
44RD input read strobe input, active low, pull, while the clearance for the watchdog input
33WR write strobe input input, active low, pull-
2723CS input chip select input, active low with pull-down
22ALE enter an address latch enable, active high, pull the falling edge latch data bus can be multiplexed address
11INT output interrupt output, transmission success, the low effective
Partially supported by 585 bi-directional 4-bit address input A3A0 line pull can be directly input and output independently controlled
2421SCL output I2C interface clock line
2320SDA bi-directional I2C interface data cable, open-drain output pull-
2522RST output power on reset and watchdog reset, active high
RST does not support output of 26 power-on reset and watchdog reset, active low