Access ports, port selector with enable outputs, and TDI/TDO multiplexer
AssigneeTexas Instruments Incorporated
InventorLee D. Whetsel
Life of this patent
Estimating the term…
Abstract
The disclosure describes a novel method and apparatuses for allowing a controller to select and access different types of access ports in a device. The selecting and accessing of the access ports is achieved using only the dedicated TDI, TMS, TCK, and TDO signal terminals of the device. The selecting and accessing of device access ports can be achieved when a single device is connected to the controller, when multiple devices are placed in a daisy-chain arrangement and connected to the controller, or when multiple devices are placed in a addressable parallel arrangement and connected to the controller. Additional embodiments are also provided and described in the disclosure.
Claims15
An integrated circuit comprising:
- (a) a data in input lead, a mode select input lead, a clock input lead, and a data out output lead;
- (b) a first access port having data input coupled to the data in input lead, an input coupled to the mode select input lead, an input coupled to the test clock input lead, an enable input, and a data output coupled to the data out output lead;
- (c) a second access port having data input coupled to the data in input lead, an input coupled to the mode select input lead, an input coupled to the test clock input lead, an enable input, and a data output coupled to the data out output lead;
- (d) a first multiplexer having an input coupled to the data out output lead of the first access port, an input coupled to the data in input lead, a control input, and an output coupled to the data out output lead;
- and
- (e) a port selector having a port select register and a state machine,
- the port select register having:
- an input coupled to the data in input lead,
- control inputs,
- a first enable output coupled to the enable input of the first access port,
- a second enable output coupled to the enable input of the second access port, and
- a control output coupled to the control input of the first multiplexer, and the state machine having:
- an input coupled to the mode select input lead,
- an input coupled to the clock input lead, and
- control outputs coupled to the control inputs of the port select register.
Dependencies are inferred from the claim text.