SX Device Programming Specifications Rev 2.2 10 © 2000 Scenix Semiconductor, Inc. All rights reserved. www.scenix.com clocking, stack size, and Watchdog options. To read this initial memory location, the programmer unit
issues the “Read Data” command and reads the 12 bits of data in the data cycle portion of the frame. To read the word at the next address, the programmer unit issues the “Increment Address” command.
This increments an internal pointer to the program memory, allowing access to address 000h. It does
not matter what the programmer unit does during the 12 data cycles of the “Increment Address” frame.
Following this frame, the programmer issues another “Read Data” command and reads the 12 bits of
data in the data cycle portion of the frame. This sequence is repeated to read consecutive memory locations. The first memory location is FFFh
(2K device) or 1FFFh (4K device) (the FUSE word register), followed by 000h, 001h, 002h, and so on
up to the top memory address, 7FFh or FFFh. The programmer can skip over any number of memory
locations  by  repeating  the  “Increment  Address”  command  consecutively,  without  using  the  “Read
Data” command. The “Increment Address” command must be used 2,048 or 4,096 times to traverse
the whole program memory and 4096 (2K device) or 8192 (4K device) times for wrap around. 2.10 Programming the Memory To program the EEPROM program memory, you use three commands: “Load Data” to load the a word
to be written to a memory location, “Program Data” to write the word into memory, and “Increment
Address” to change the memory address pointer from one location to the next. Upon entry into the ISP mode, the ISP logic is initially set to access the FUSE word. To program this
memory location, the programmer unit issues the “Load Data” command and writes the 12 bits of data
in the data cycle portion of the frame. Then it issues a “Program Data” command to write the loaded
word. It does not matter what the programmer unit does during the 12 data cycles of the “Program Data”  frame.  This  command  must  be  repeated  a  certain  number  of  times  in  order  to  program  the register reliably, as explained earlier. After program the FUSE word, READ explicitly the FUSE word to update the new value. FUSE word will not be updated with the new value until this READ is done. To  program  the  word  at  the  next  address,  the  programmer  unit  issues  the  “Increment  Address”
command, which increments the internal pointer to access the words at address 000h. Following the
“Increment Address” frame, the programmer issues another “Load Data” command and writes the 12 bits  of  data  in  the  data  cycle  portion  of  the  frame.  Then  it  issues  the  “Program  Data”  command consecutively for a certain number of frames. This sequence is repeated to program consecutive memory locations. The first memory location is
FFFh (2K device) or 1FFFh (4K device) (the FUSE word register), followed by 000h, 001h, 002h, and
so on up to the top memory address, 7FFh or FFFh. The programmer can skip over any number of
memory locations by repeating the “Increment Address” command consecutively. 2.11 Trimming the Internal RC Clock Bits 11, 9 and 8 of FUSEX word are used to calibrate the internal clock. After erase, these bits become
1 and the internal RC clock is trimmed to the slowest speed. It is always advisable to change those
trimming bits by one count so that the internal clock doesn’t change speed drastically, which may cause