參數(shù)資料
型號： PIC16C745/JW
廠商： Microchip Technology
文件頁數(shù)： 131/165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
PIC16C745/765
DS41124C-page 68
Preliminary
2000 Microchip Technology Inc.
10.6
Buffer Descriptor Table (BDT)
To efficiently manage USB endpoint communications
the USB implements a Buffer Descriptor Table (BDT)
in register space. Every endpoint requires a 4 byte
Buffer Descriptor (BD) entry. Because the buffers are
shared between the MCU and the USB, a simple
semaphore mechanism is used to distinguish which is
allowed to update the BD and buffers in system mem-
ory. The UOWN bit is cleared when the BD entry is
“owned” by the MCU. When the UOWN bit is set to 1,
the BD entry and the buffer in system memory is
owned by the USB. The MCU should not modify the
BD or its corresponding data buffer.
The Buffer Descriptors provide endpoint buffer control
information for the USB and MCU. The Buffer Descrip-
tors have different meaning based on the value of the
UOWN bit.
The USB Controller uses the data stored in the BDs
when UOWN = 1 to determine:
Data0 or Data1 PID
Data toggle synchronization enable
Number of bytes to be transmitted or received
Starting location of the buffer
The MCU uses the data stored in the BDs when
UOWN = 0 to determine:
Data0 or Data1 PID
The received TOKEN PID
Number of bytes transmitted or received
Each endpoint has a 4 byte Buffer Descriptor and
points to a data buffer in the USB dual port register
space. Control of the BD and buffer would typically be
handled in the following fashion:
The MCU verifies UOWN = 0, sets the BDndAL to
point to the start of a buffer, if necessary fills the
buffer, then sets the BDndST byte to the desired
value with UOWN = 1.
When the host commands an in or out transac-
tion, the Serial Interface Engine (SIE) performs
the following:
- Get the buffer address
- Read or write the buffer
- Update the USTAT register
- Update the buffer descriptors with the packet
ID (PID) value
- Set the data 0/1 bit
- Update the byte count
- Clear the UOWN bit
The MCU is interrupted and reads the USTAT,
translates that value to a BD, where the UOWN,
PID, Data 0/1, and byte count values are
checked.
Warning: The bit entries should be written as a
whole word instead of using BSF, BCF to
affect individual bits. This is because of
the dual meaning of the bits. Bit sets and
clears may leave other bits set incor-
rectly and present incorrect data to the
SIE.
745cov.book Page 68 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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