Hardware Overview

Chapter 2

The USB keyboard/hub EVM features the TUSB2136 and the TPS2149 made by Texas Instruments. The EVM is a two-board set made up of a stand alone two-port hub (edge #6436539) and a miniature QWERTY keyboard (edge #6436540). Jumpers (0-Ω resistors) and jumper blocks provided on the EVM are installed with the factory settings. The settings are described in Table 3–2. Review all setting changes prior to powering the EVM. Improper settings could result in damage to some of the EVM components. The factory settings allow the EVM to operate using a 12-MHz crystal along with an I2C EEPROM. The EVM has also been configured to work only in bus-powered mode. The firmware installed at the factory and stored in the EEPROM allows the EVM to function as a two port keyboard hub. Users are responsible for developing their own application firmware for the target hardware device.

The EVM uses a TUSB2136, USB keyboard/hub controller, made by Texas Instruments, to communicate with the host and the downstream devices. A USB cable is needed to connect the root hub of the PC to the EVM type B connector (J5). The downstream devices connect to the EVM via the J6 and J7 connectors. These downstream devices are powered through the TPS2149, a power management device that integrates an LDO and two power switches into one small package. The LDO is used to provide power to the TUSB2136. The USB specification requires that downstream ports remain off until enumeration is complete. Together, the TUSB2136 and the TPS2149 ensure the hub meets this requirement. Two other connectors, J3 and J4, allow easy connection to the TUSB2136 general-purpose I/O lines. These lines are used to implement the keyboard function. The miniature QWERTY keyboard plugs directly into J3 and J4 to implement a fully functional keyboard.

Jumpers, test points, and LEDs have been added for testing, troubleshooting and debugging purposes. There are test points on the differential pair lines of the upstream B-type connector and the two downstream A-type connectors. The I2C port can be probed directly on the EEPROM. Six LEDs are provided for quick feedback during firmware debugging or as status information. One LED (D1) is fixed to provide power and suspend status of the TUSB2136 device. An RS–232 port is available for monitoring 8052 MCU activity. The port uses a one-to-one cable and not a null-modem cable.

Hardware Overview

2-1

TUSB2136 specifications

Texas Instruments (TI) is a renowned leader in semiconductor technology, and one of its notable offerings is the TUSB2136. This USB 2.0 hub controller is specifically designed to facilitate seamless connectivity in various electronic applications, making it a vital component in today’s digital ecosystem.

The TUSB2136 is based on USB technology, supporting a high-speed data transmission rate of up to 480 Mbps. One of its key features is the ability to manage multiple USB ports, specifically providing support for up to three downstream ports. This allows a single TUSB2136 chip to connect multiple devices, significantly enhancing system design flexibility and efficiency.

A significant advantage of the TUSB2136 is its low power consumption, which is crucial for battery-operated devices. The controller incorporates a low-power sleep mode that helps reduce energy consumption when the device is inactive, thus extending battery life. Additionally, it complies with USB Power Delivery specifications, allowing for efficient power management and distribution across connected devices.

The TUSB2136 is built on TI's proprietary technology, which enhances reliability and performance. It utilizes integrated supervisory and control functionality that ensures proper function and reduces the need for external circuitry. This integration leads to simplified designs and smaller footprints, which is especially beneficial in compact devices.

Another noteworthy characteristic of the TUSB2136 is its robust support for a variety of communication protocols. It is designed to handle different USB device classes seamlessly, supporting functions such as mass storage, human interface devices, and audio devices. This versatility makes it an ideal choice for a wide range of applications, from consumer electronics to industrial automation.

The device also features advanced fault detection capabilities. In the event of a short circuit or other issues, the TUSB2136 can help isolate the problem, ensuring system reliability and user safety. Its compliance with USB specifications means that designers can integrate it into their systems with confidence that it meets industry standards.

In summary, the Texas Instruments TUSB2136 USB hub controller stands out with its multi-port support, low power consumption, high data transfer rates, and reliability. It represents a significant advancement in USB connectivity technology, making it an essential component for designers looking to enhance their products with efficient and flexible USB solutions. As technology continues to evolve, the versatility and features of the TUSB2136 will undoubtedly play a crucial role in the development of future electronic devices.