Echelon FT 3150 Smart Transceiver - Manual (Page 34)

Chapter 2 - Hardware Resources
28 FT 3120 / FT 3150 Smart Transceiver Data Book
Table 2.10 Service LED Behavior During Different States
The SERVICE pin is active low and the service pin message is sent once maximum per SERVICE pin transition. The
service pin message goes into the next available priority or non-priority output network buffer.
Integrity Mechanisms
Memory Integrity Using Checksums
To ensure the integrity of the memory of the FT Smart Transceiver , the Neuron firmware maintains a number of
checksums. Each checksum is a single byte and is the two’s complement of the sum of all bytes it covers. These
checksums are verified during reset processing and also on a continual basis via a background diagnostic process.
There are three main checksums used to verify the integrity of the memory of the FT Smart Transceiver:
• Configuration image checksum
• Application image checksum
• System image checksum (off-chip system image only)
The configuration image checksum covers the network configuration information and communication parameters
residing in the on-chip EEPROM. The default behavior is that a configuration checksum error causes the device to go
to the unconfigured state. Refer to Table 2.12 for other options.
The application image checksum covers the application code in both on-chip EEPROM and any application code in
off-chip EEPROM, NVRAM, or flash memory. This checksum can optionally be extended to cover any application
code in off-chip ROM as well. The default behavior is that an application checksum error causes the device to go to
the applicationless state. Application read/write data residing in EEPROM, NVRAM, or flash is not checksummed.
Refer to Table 2.12 for other options.
Table 2.11 Checksum Coverage of FT Smart Transceiver Memory Areas
In the FT 3150 Smart Transceiver, all memory areas listed in Figure 2.11 except for on-chip EEPROM code have
their own checksum so that checksum errors can be further isolated. An unconfigured or configured device
continually checks its application checksum in the background at the rate of 1 byte per iteration through the main loop
of the network processor (3 bytes per millisecond when running at 10MHz with no network activity).
Device State
0xF015
State Code Service LED
Applicationless and Unconfigured 3 On
Unconfigured (but with an Application) 2 Flashing
Configured, Hard Offline 6 Off
Configured 4 Off
3150 Defective External Memory — On
Memory Area Checksum
System image (optionally covered by application
checksum on the FT 3150) System
Any off-chip ROM code (optionally covered by
Application checksum on the FT 3150) Application
Any off-chip flash, EEPROM, or NVRAM code Application
Any off-chip RAM code Application
Configuration image Configuration
All on-chip EEPROM code Application