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Enhanced SCAN bridge Multidrop Addressable IEEE 1149.1 (JTAG) Port
National Semiconductor
Description
The SCANSTA111 extends the IEEE Std. 1149.1 test bus into a multidrop test bus environment. The advantage of a multidrop approach over a single serial scan chain is improved test throughput and the ability to remove a board from the system and retain test access to the remaining modules. Each SCANSTA111 supports up to 3 local IEEE1149.1 scan rings which can be accessed individually or combined serially. Addressing is accomplished by loading the instruction register with a value matching that of the Slot inputs. Backplane and inter-board testing can easily be accomplished by parking the local TAP Controllers in one of the stable TAP Controller states via a Park instruction. The 32-bit TCK counter enables built in self test operations to be performed on one port while other scan chains are simultaneously tested.
Features
• True IEEE 1149.1 hierarchical and multidrop addressable capability
• The 7 slot inputs support up to 121 unique addresses, an Interrogation Address, Broadcast Address, and 4 Multi-cast Group Addresses (address 000000 is reserved)
• 3 IEEE 1149.1-compatible configurable local scan ports
• Mode Register0 allows local TAPs to be bypassed, selected for insertion into the scan chain individually, or serially in groups of two or three
• Transparent Mode can be enabled with a single instruction to conveniently buffer the backplane IEEE 1149.1 pins to those on a single local scan port
• LSP ACTIVE outputs provide local port enable signals for analog busses supporting IEEE 1149.4.
• General purpose local port passthrough bits are useful for delivering write pulses for FPGA programming or monitoring device status.
• Known Power-up state
• TRST# on all local scan ports
• 32-bit TCK counter
• 16-bit LFSR Signature Compactor
• Local TAPs can become TRI-STATE via the OE# input to allow an alternate test master to take control of the local TAPs (LSP0-2 have a TRI-STATE notification output)
• 3.0-3.6V VCC Supply Operation
• Power-off high impedance inputs and outputs
• Supports live insertion/withdrawal
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