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參數(shù)資料
| 型號： | PIC16C745/JW |
| 廠商： | Microchip Technology |
| 文件頁數(shù)： | 120/165頁 |
| 文件大?。?/td> | 0K |
| 描述： | IC MCU EPROM8KX14 USB A/D 28CDIP |
| 標(biāo)準(zhǔn)包裝： | 15 |
| 系列： | PIC® 16C |
| 核心處理器： | PIC |
| 芯體尺寸： | 8-位 |
| 速度： | 24MHz |
| 連通性： | SCI，UART/USART，USB |
| 外圍設(shè)備： | 欠壓檢測/復(fù)位，POR，PWM，WDT |
| 輸入/輸出數(shù)： | 22 |
| 程序存儲器容量： | 14KB（8K x 14） |
| 程序存儲器類型： | EPROM，UV |
| RAM 容量： | 256 x 8 |
| 電壓 - 電源 (Vcc/Vdd)： | 4.35 V ~ 5.25 V |
| 數(shù)據(jù)轉(zhuǎn)換器： | A/D 5x8b |
| 振蕩器型： | 外部 |
| 工作溫度： | 0°C ~ 70°C |
| 封裝/外殼： | 28-CDIP（0.300"，7.62mm）窗口 |
| 包裝： | 管件 |
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PIC16C745/765
DS41124C-page 58
Preliminary
2000 Microchip Technology Inc.
The Device descriptor provides general information
such as manufacturer, product number, serial number,
USB device class the product falls under, and the
number of different configurations supported. There
can only be one Device descriptor for any given appli-
cation.
The Configuration descriptor provides information on
the power requirements of the device and how many
different interfaces are supported when in this configu-
ration. There may be more than one configuration for
each device, (i.e., a high power device may also sup-
port a low power configuration).
The Interface descriptor details the number of end-
points used in this interface, as well as the class driver
to use should the device support functions in more
than just one device class. There can only be one
Interface descriptor for each configuration.
The Endpoint descriptor details the actual registers for
a given function. Information is stored about the trans-
fer types supported, direction (In/Out), bandwidth
requirements and polling interval. There may be more
than one endpoint in a device, and endpoints may be
shared between different interfaces.
Many of the four descriptors listed above will reference
or index different String descriptors. String descriptors
are used to provide vendor specific or application spe-
cific information. They may be optional and are
encoded in “Unicode” format.
10.1.7
DEVICE CLASSES/CLASS DRIVERS
Operating systems provide drivers which group func-
tions together by common device types called classes.
Examples of device classes include, but are not limited
to, storage, audio, communications and HID (Human
Interface). Class drivers for a given application are ref-
erenced in both the Device descriptor and Interface
descriptor. Most applications can find a Class Driver
which supports the majority of their function/command
needs. Vendors who have a requirement for specific
commands which are not supported by any of the
standard class drivers may provide a vendor specific
“.inf” file or driver for extra support.
10.1.8
SUMMARY
While a complete USB overview is beyond the scope
of this document, a few key concepts must be noted.
Low speed communication is designed for devices,
which in the past, used an interrupt to communicate
with the host. In the USB scheme, devices do not
directly interrupt the processor when they have data.
Instead the host periodically polls each device to see if
they have any data. This polling rate is negotiated
between the device and host, giving the system a
guaranteed latency.
For more details on USB, see the USB V1.1 spec,
available from the USB website at www.usb.org.
10.2
Introduction
The PIC16C745/765 USB peripheral module supports
Low Speed control and interrupt (IN and OUT) trans-
fers only. The implementation supports 3 endpoint
numbers (0, 1, 2) for a total of 6 endpoints.
The following terms are used in the description of the
USB module:
MCU - The core processor and corresponding
firmware
SIE - Serial Interface Engine: That part of the
USB that performs functions such as CRC gener-
ation and clocking of the D+ and D- signals.
USB - The USB module including SIE and
registers
Bit Stuffing - forces insertion of a transition on D+
and D- to maintain clock synchronization
BD - Buffer Descriptor
BDT - Buffer Descriptor Table
EP - Endpoint (combination of endpoint number
and direction)
IN - Packet transfer into the host
OUT - Packet transfer out of the host
10.3
USB Transaction
When the USB transmits or receives data the SIE will
first check that the corresponding endpoint and direc-
tion Buffer Description UOWN bit equals 1. The USB
will move the data to or from the corresponding buffer.
When the TOKEN is complete, the USB will update the
BD status and change the UOWN bit to 0. The USTAT
register is updated and the TOK_DNE interrupt is set.
When the MCU processes the TOK_DNE interrupt it
reads the USTAT register, which gives the MCU the
information it needs to process the endpoint. At this
point the MCU will process the data and set the corre-
sponding UOWN bit. Figure 10-1 shows a time line of
how a typical USB token would be processed.
10.4
Firmware Support
Microchip provides a comprehensive support library of
standard chapter 9 USB commands. These libraries
provide a software layer to insulate the application
software from having to handle the complexities of the
USB protocol. A simple Put/Get interface is imple-
mented to allow most of the USB processing to take
place in the background within the USB interrupt ser-
vice routine. Applications are encouraged to use the
provided libraries during both enumeration and config-
ured operation.
745cov.book Page 58 Wednesday, August 2, 2000 8:24 AM
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| PIC16C745T-I/SO | 功能描述:8位微控制器 -MCU 14KB 256 RAM 22 I/O RoHS:否 制造商:Silicon Labs 核心:8051 處理器系列:C8051F39x 數(shù)據(jù)總線寬度:8 bit 最大時鐘頻率:50 MHz 程序存儲器大小:16 KB 數(shù)據(jù) RAM 大小:1 KB 片上 ADC:Yes 工作電源電壓:1.8 V to 3.6 V 工作溫度范圍:- 40 C to + 105 C 封裝 / 箱體:QFN-20 安裝風(fēng)格:SMD/SMT |
| PIC16C74A/JW | 功能描述:8位微控制器 -MCU 7KB 192 RAM 33 I/O RoHS:否 制造商:Silicon Labs 核心:8051 處理器系列:C8051F39x 數(shù)據(jù)總線寬度:8 bit 最大時鐘頻率:50 MHz 程序存儲器大小:16 KB 數(shù)據(jù) RAM 大小:1 KB 片上 ADC:Yes 工作電源電壓:1.8 V to 3.6 V 工作溫度范圍:- 40 C to + 105 C 封裝 / 箱體:QFN-20 安裝風(fēng)格:SMD/SMT |
| PIC16C74A-04/L | 功能描述:8位微控制器 -MCU 7KB 192 RAM 33 I/O RoHS:否 制造商:Silicon Labs 核心:8051 處理器系列:C8051F39x 數(shù)據(jù)總線寬度:8 bit 最大時鐘頻率:50 MHz 程序存儲器大小:16 KB 數(shù)據(jù) RAM 大小:1 KB 片上 ADC:Yes 工作電源電壓:1.8 V to 3.6 V 工作溫度范圍:- 40 C to + 105 C 封裝 / 箱體:QFN-20 安裝風(fēng)格:SMD/SMT |
| PIC16C74A-04/L | 制造商:Microchip Technology Inc 功能描述:8BIT CMOS MCU SMD 16C74 PLCC44 |
| PIC16C74A-04/P | 功能描述:8位微控制器 -MCU 7KB 192 RAM 33 I/O RoHS:否 制造商:Silicon Labs 核心:8051 處理器系列:C8051F39x 數(shù)據(jù)總線寬度:8 bit 最大時鐘頻率:50 MHz 程序存儲器大小:16 KB 數(shù)據(jù) RAM 大小:1 KB 片上 ADC:Yes 工作電源電壓:1.8 V to 3.6 V 工作溫度范圍:- 40 C to + 105 C 封裝 / 箱體:QFN-20 安裝風(fēng)格:SMD/SMT |
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