COP8CCR9IMT7SLASHNOPB datasheet(37/111 Pages) TI1

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COP8CBR9, COP8CCR9, COP8CDR9

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SNOS535I – OCTOBER 2000 – REVISED MARCH 2013

Table 5-7. PGMTIM Register Format (continued)

PGMTIM

CKI Frequency Range

2 MHz–2.67 MHz

2.625 MHz–3.5 MHz

3.5 MHz–4.67 MHz

4.5 MHz–6 MHz

6 MHz–8 MHz

7.5 MHz–10 MHz

R/W

5.10.4 MANEUVERING BACK AND FORTH BETWEEN FLASH MEMORY AND BOOT ROM

When using ISP, at some point, it will be necessary to maneuver between the flash program memory and

the Boot ROM, even when using customized ISP routines. This is because it's not possible to execute

from the flash program memory while it's being programmed.

Two instructions are available to perform the jumping back and forth: Jump to Boot (JSRB) and Return to

Flash (RETF). The JSRB instruction is used to jump from flash memory to Boot ROM, and the RETF is

used to return from the Boot ROM back to the flash program memory. See Instruction Set for specific

details on the operation of these instructions.

The JSRB instruction must be used in conjunction with the Key register. This is to prevent jumping to the

Boot ROM in the event of run-away software. For the JSRB instruction to actually jump to the Boot ROM,

the Key bit must be set. This is done by writing the value shown in Table 5-8 to the Key register. The Key

is a 6 bit key and if the key matches, the KEY bit will be set for 8 instruction cycles. The JSRB instruction

must be executed while the KEY bit is set. If the KEY does not match, then the KEY bit will not be set and

the JSRB will jump to the specified location in the flash memory. In emulation mode, if a breakpoint is

encountered while the KEY is set, the counter that counts the instruction cycles will be frozen until the

breakpoint condition is cleared. If an interrupt occurs while the key is set, the key will expire before

interrupt service is complete. It is recommended that the software globally disable interrupts before setting

the key. The Key register is a memory mapped register. Its format when writing is shown in Table 5-8. In

normal operation, it is not necessary to test the KEY bit before using the JSRB instruction. The additional

instructions required to test the key may cause the key to time-out before the JSRB can be executed.

Table 5-8. KEY Register Write Format

KEY When Writing

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

Bits 7–2:

Key value that must be written to set the KEY bit.

Bits 1–0:

Don't care.

5.10.5 FORCED EXECUTION FROM BOOT ROM

When the user is developing a customized ISP routine, code lockups due to software errors may be

encountered. The normal, and preferred, method to recover from these conditions is to reprogram the

device with the corrected code by either an external parallel programmer or the emulation tools. As a last

resort, when this equipment is not available, there is a hardware method to get out of these lockups and

force execution from the Boot ROM MICROWIRE/PLUS routine. The customer will then be able to erase

the Flash Memory code and start over.

Functional Description

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