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循序渐进理解恒流源电路
由 电阻 构成的 恒流源 模型一： 1个三极管 简单 三极管 恒流源 改进 模型二： 2个三极管 改进1： 改进2: 由 电阻 构成的 恒流源 缺点: 高压电源 不常用 大电阻 会引起功耗大 灵活性差(如果想得到不同的供电电流，需要不停的更换大电阻) 模型一： 1个三极管 简单 三极管 恒流源 让三极管工作在放大... -
7.4 Root Hub Partition
All registers included in this partition are dedicated to the USB Root Hub which is an integral part of the Host Controller though still a functionally separate entity. The HCD em... -
7.4.4 HcRhPortStatus[1:NDP] Register
字段功能说明 The HcRhPortStatus[1:NDP] register is used to control and report port events on a per-port basis. NumberDownstreamPorts represents the number of HcRhPortStatus registers t... -
3.2 Data Transfer Types
There are four data transfer types defined in USB. Each type is optimized to match the service requirements between the client software and the USB device. The four types are:· In... -
7.4.3 HcRhStatus Register
图7-21：HcRhStatus寄存器结构说明 寄存器位布局（31:0） 字段功能详述 7.4.3 HcRhStatus Register The HcRhStatus register is divided into two parts. The lower word of a Dword represents the Hub Status fi... -
7.1.4 HcInterruptStatus Register
This register provides status on various events that cause hardware interrupts. When an event occurs, Host Controller sets the corresponding bit in this register. When a bit becom... -
11.15.1 Standard Descriptors
Device Descriptor 设备描述符 Interface Descriptor 接口描述符 Configuration Descriptor 配置描述符 Endpoint Descriptor (for Status Change Endpoint) 端点描述符（用于状态变更端点） The hub class pre-define... -
7.2.2 HcPeriodCurrentED
The HcPeriodCurrentED register contains the physical address of the current Isochronous or Interrupt Endpoint Descriptor. HcPeriodCurrentED寄存器包含当前等时或中断端点描述符的物理地址。 图 7-8：H... -
4.4.2.3 HccaDoneHead
When a TD is complete (with or without an error) it is unlinked from the queue that it is on and linked to the Done Queue. The Host Controller maintains a physical pointer to the ... -
电流源的内阻
无穷大 1. 从定义出发：电流源的任务是“输出恒定电流” 2. 从实际应用出发：内阻决定了“带载能力” 总结 笔记 无穷大 要理解“为什么理想电流源的内阻必须是无穷大”，我们可以从电流源的定义 和实际应用场景 两个角度来拆解。 1. 从定义出发：电流源的任务是“输出恒定电流” 一个理想电流源的核心任务是：无论其两端电压如何变化，它输出的...