Although UESCODE is not defined in the JTAG specification, this instruction uses the JTAG state machine to shift a signature out of the device, thus providing the same version control capability as the USERCODE instruction. UESCODE can use one or more instructions to read a signature out of the device. Since UESCODE is an Altera® instruction, you must use a Jam file (.jam) generated by the MAX PLUS® II software to read out the instruction.
You can set the USERCODE or UESCODEregister in the MAX PLUS II software via the User Code option (Assign menu -> Global Project Device Options). Table 1 lists the USERCODE or UESCODE register length for Altera devices.
| Table 1. USERCODE & UESCODE Register Lengths | ||
| Device | Instruction | Length (bits) |
| APEX™ 20K | USERCODE | 32 |
| FLEX® 10K | USERCODE | 32 (1) |
| FLEX 10KE | USERCODE | 32 (1) |
| FLEX 8000 | NA | NA |
| FLEX 6000 | NA | NA |
| MAX® 9000A | UESCODE | 16 |
| MAX 7000A | UESCODE | 16 |
| MAX 7000AE | USERCODE | 32 |
| MAX 7000B | USERCODE | 32 |
| MAX 3000A | USERCODE | 32 |
| Configuration devices | USERCODE | 32 |
Note:
(1) Seven bits determined by the user, 25 bits predetermined.
For more information on USERCODE and UESCODE, refer to AN 39: IEEE 1149.1(JTAG) Boundary-Scan Testing in Altera Devices (PDF).