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ST72P63BE1M1 Datasheet(PDF) 78 Page - STMicroelectronics |
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ST72P63BE1M1 Datasheet(HTML) 78 Page - STMicroelectronics |
78 / 145 page ![]() ST7263BDx ST7263BHx ST7263BKx ST7263BE 78/145 12.4 USB interface (USB) 12.4.1 Introduction The USB Interface implements a low-speed func- tion interface between the USB and the ST7 mi- crocontroller. It is a highly integrated circuit which includes the transceiver, 3.3 voltage regulator, SIE and DMA. No external components are needed apart from the external pull-up on USBDM for low speed recognition by the USB host. The use of DMA architecture allows the endpoint definition to be completely flexible. Endpoints can be config- ured by software as in or out. 12.4.2 Main features ■ USB Specification Version 1.1 Compliant ■ Supports Low-Speed USB Protocol ■ Two or Three Endpoints (including default one) depending on the device (see device feature list and register map) ■ CRC generation/checking, NRZI encoding/ decoding and bit-stuffing ■ USB Suspend/Resume operations ■ DMA Data transfers ■ On-Chip 3.3V Regulator ■ On-Chip USB Transceiver 12.4.3 Functional description The block diagram in Figure 41, gives an overview of the USB interface hardware. For general information on the USB, refer to the “Universal Serial Bus Specifications” document available at http//:www.usb.org. Serial interface engine The SIE (serial interface engine) interfaces with the USB, via the transceiver. The SIE processes tokens, handles data transmis- sion/reception, and handshaking as required by the USB standard. It also performs frame format- ting, including CRC generation and checking. Endpoints The Endpoint registers indicate if the microcontrol- ler is ready to transmit/receive, and how many bytes need to be transmitted. DMA When a token for a valid Endpoint is recognized by the USB interface, the related data transfer takes place, using DMA. At the end of the transaction, an interrupt is generated. Interrupts By reading the Interrupt Status register, applica- tion software can know which USB event has oc- curred. Figure 41. USB block diagram CPU MEMORY Transceiver 3.3V Voltage Regulator SIE ENDPOINT DMA INTERRUPT Address, and interrupts USBDM USBDP USBVCC 6 MHz REGISTERS REGISTERS data buses USBGND |