DESIGN OF A CUSTOM ASIC INCORPORATING CAN™ AND 1 ...

algorithm. In addition to this, correct operation was also tested for the WRITE_SP (0x0Fh),
READ_SP (0xAAh), and SKIP_ROM (0xCC) commands.
Figure 5.12 Scratchpad Memory Test Setup.
Table 5.6 Scratchpad Memory (scratchpad_integrity) Test Results.
1 – Wire® Device Type 1 – Wire Probe Cables Length of test Hot Swapped Failures
DS1963S[89]
Yes No
DS1994[82] Yes No
DS1996[83] DS1402-RP8+[80] 60 min
Yes No
DS1995[90] Yes No
DS1972[85] Yes No
Not to be misleading, the absence of failures in Table 5.6 is only due to the fact that a
single 1 – Wire® device exists and the SKIP_ROM (0xCC) command was used instead of the
READ_ROM (0x33) command. The SKIP_ROM (0xCC) command can save time in a single
slave system by allowing the 1 – Wire® Master to access the memory functions without
providing the 64-bit ROM_ID code. So in this case hot swapping would be successful since the
1 – Wire® Master would not care about the 1 – Wire® slave device ROM_ID code it was
addressing. If more than a single 1 – Wire® slave device had been present on the 1 – Wire®
network, it is possible that failures could have occurred. Since the SKIP_ROM (0xCC)
command is typically used to select all devices regardless of their ROM_ID, more testing under
circumstances with multiple 1 – Wire® slave devices is needed for conclusive evidence on
failure rates in this case.
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