MPC885 PowerQUICC Family Reference Manual, Rev. 2
Freescale Semiconductor
54-1
Chapter 54
IEEE 1149.1 Test Access Port
The MPC885 provides a dedicated user-accessible test access port (TAP) that is fully compatible with the
IEEE 1149.1 Standard Test Access Port and Boundary Scan Architecture. Problems associated with testing
high-density circuit boards have led to development of this standard under the sponsorship of the Test
Technology Committee of IEEE and the Joint Test Action Group (JTAG). The MPC885 implementation
supports circuit-board test strategies based on this standard.
The TAP consists of five dedicated signals, a 16-state TAP controller, and two test data registers. A
boundary scan register links all device signals into a single shift register. The test logic, implemented using
static logic design, operates independently of the device system logic. The MPC885 TAP implementation
provides the capability to:
•
Perform boundary scan operations to check circuit-board electrical continuity.
•
Bypass the MPC885 for a given circuit-board test by effectively reducing the boundary scan
register to a single cell.
•
Sample the MPC885 system signals during operation and transparently shift out the result in the
boundary scan register.
•
Disable the output drive to signals during circuit-board testing.
54.1
Overview
The MPC885 TAP implementation includes a TAP controller, a 4-bit instruction register, and two test
registers (a 1-bit bypass register and a 475-bit boundary scan register). The TAP interface consists of the
following signals:
•
TCK—A test clock input to synchronize the test logic.
•
TMS—A test mode select input (with an internal pull-up resistor) that is sampled on the
rising edge of TCK to sequence the TAP controller’s state machine.
•
TDI—A test data input (with an internal pull-up resistor) that is sampled on the rising edge
of TCK.
•
TDO—A three-statable test data output that is actively driven in the shift-IR and shift-DR
controller states. TDO changes on the falling edge of TCK.
•
TRST
—
An asynchronous reset with an internal pull-up resistor that provides initialization
of the TAP controller and other logic required by the standard.
Summary of Contents for PowerQUICC MPC870
Page 98: ...MPC885 PowerQUICC Family Reference Manual Rev 2 I 4 Freescale Semiconductor ...
Page 118: ...MPC885 Overview MPC885 PowerQUICC Family Reference Manual Rev 2 1 20 Freescale Semiconductor ...
Page 158: ...The MPC8xx Core MPC885 PowerQUICC Family Reference Manual Rev 2 3 18 Freescale Semiconductor ...
Page 288: ...MPC885 PowerQUICC Family Reference Manual Rev 2 III 4 Freescale Semiconductor ...
Page 554: ...MPC885 PowerQUICC Family Reference Manual Rev 2 V 6 Freescale Semiconductor ...
Page 1090: ...UTOPIA Interface MPC885 PowerQUICC Family Reference Manual Rev 2 43 8 Freescale Semiconductor ...
Page 1312: ...Byte Ordering MPC885 PowerQUICC Family Reference Manual Rev 2 A 8 Freescale Semiconductor ...
Page 1336: ...MPC885 PowerQUICC Family Reference Manual Rev 2 D 16 Freescale Semiconductor ...
Page 1358: ...MPC885 PowerQUICC Family Reference Manual Rev 2 D 38 Freescale Semiconductor ...
Page 1370: ...MPC880 MPC885 PowerQUICC Family Reference Manual Rev 2 E 4 Freescale Semiconductor ...
Page 1386: ...Revision History MPC885 PowerQUICC Family Reference Manual Rev 2 I 2 Freescale Semiconductor ...