Scan circuits formed peripheral of core circuits with control leads
An integrated circuit carries an intellectual property core. The intellectual property core includes a test access port 39 with test data input leads 15, test data output leads 13, control leads 17 and an external register present, ERP lead 37 . A scan register 25 encompasses the intellectual property core and ERP lead 37 carries a signal indicating the presence of the scan register.
1. An integrated circuit comprising:
A. a semiconductor substrate;
B. functional circuits formed on the substrate, the functional circuits including at least one set of IP core circuits, the IP core circuits including:
i. core functional circuits formed on the substrate, the core functional circuits forming a periphery on the substrate and having core functional input leads and core functional output leads that extend beyond that periphery, the core functional input leads and core functional output leads being free of any connection to any boundary scan circuits within the periphery of the core functional circuits; and
ii. test circuits formed on the substrate within the periphery of the core functional circuits, the test circuits including a test access port and test data registers, the test circuits including:
a. a test data input lead extending beyond the periphery of the core functional circuits;
b. a test data output lead extending beyond the periphery of the core functional circuits;
c. a test clock lead extending beyond the periphery of the core functional circuits;
d. a test mode select lead extending beyond the periphery of the core functional circuits;
e. a second test data input lead extending beyond the periphery of the core functional circuits;
f. a second test data output lead extending beyond the periphery of the core functional circuits;
g. control signal leads extending beyond the periphery of the core functional circuit; and
h. external register present leads extending beyond the periphery of the core functional circuit; and
C. first scan circuits serially formed on the substrate outside of the periphery of the IP core circuits, the first scan circuits being formed between and connecting together the core functional input leads and the rest of the functional circuits, the first scan circuits being formed between and connecting together the core functional output leads and the rest of the functional circuits, and the first scan circuits being connected to the second test data input lead, the second test data output lead, and the control signal leads; and
D. second scan circuits formed on the substrate outside of the periphery of the IP core circuits, the second scan circuits being separate from the first scan circuits, and the second scan circuits being connected to the second test data input lead, the second test data output lead, and the control signal leads.
2. The integrated circuit of claim 1 in which the control signal leads extend within the IP core circuits, and the test circuits include data registers connected to the test data input lead and the control signal leads.
3. The integrated circuit of claim 1 in which the first scan circuits are boundary scan circuits connected with the core functional input leads and core functional output leads.
4. The integrated circuit of claim 1 in which the second scan circuits are general purpose scan circuits free of connection with the core functional input leads and core functional output leads.
5. The integrated circuit of claim 1 in which a first external register present lead is associated with the first scan circuits and a second external register present lead is associated with the second scan circuits.