FUSEX Word

(Read/Program via Programming Command)

After the chip enters the ISP mode, the address is pointing to the FUSE word and the FUSE word location can be accessed only once. Programming the FUSE word after incrementing the address 4096 times doesn't seem work. If it is programed it before incrementing the address, it works fine.

For the SX18-28:

bit 11,9,8: IRCTRIM2:IRCTRIM0

Internal RC oscillator trim bits. This 3-bit field adjusts the operation of the internal RC oscillator to make it operate within the target frequency range 4 MHz plus or minus 8%. Parts are shipped from the factory untrimmed. The device relies on the programming toll to provide the trimming function. Each step is about 3%

• 000b = minimum frequency
• 111b = maximum frequency

bit 10: PINS

• 0 = 18 pins
• 1 = 28 pins

bit 7: OPTIONX/STACKX

OPTION Register Extension and Stack Extension. Set to 1 to disable the programmability of bit 6 and bit 7 in the OPTION register, the RTW and RTE_IE bits (in other words, to force these two bits to 1) and to limit the program stack size to two locations. Clear to 0 to enable programming of the RTW and RTE_IE bits in the OPTION register, and to extend the stack size to eight locations.

bit 6: CF ( CARRYX )

Active low – makes carry bit input to ADD and SUB instructions. Note that JMP PC+xx and CJE each have an add or subtract instruction included and so are affected by the carry bit.

bit 5,4: BOR1: BOR0

Brown-Out Reset;These bits enable or disable the brown-out reset function and set the brown-out threshold voltage as follows:

• 00b = 4.2V
• 01b = 2.6V
• 10b = 2.2V
• 11b = Brown-Out disabled

bit 3,2: BORTRIM1:BORTRIM0

Brown-Out trim bits (parts are shipped out of factory untrimmed).

bit 1,0: PB1:BP0

Configure Memory Size:

• 00b = 1 page, 1 bank
• 01b = 1 page, 2 banks
• 10b = 4 pages, 4 banks
• 11b = 4 pages, 8 banks (default configuration)

bit 7: BOSC

• BOSC Enable the stop of oscillator by pulling OSC2 low on 8 clocks More explanation needed.

Remove “Banks” column from:

MEM1:MEM0 Configured memory size on chip

• 00b = 1 page (512 words)
• 01b = 2 pages
• 10b = 4 pages
• 11b = 4 pages (default configuration)

See:

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