35
Rev. 0
APPENDIX B: CAN BASED EVALUATION
Connect 5V to 12V supply to DC2732A demo board.
Connect Ethernet patch cable between RJ45 connectors
of DC2732A and DC2617A.
Figure 51. DC2732A Demoboard
Figure 52. FSSHT, FIFOAUX, FIFOBAT, FIFOI2, FIFOI1,
FIFOAUXAVG, FIFOBATAVG, FIFOI2AVG, FIFOI1AVG Use
the Little-Endian Representation for Their Signal Data (All
Other Messages Use Big-Endian Format)
The DC2732A_CAN uses CAN messages listed in Table
1. See also DC2732A_CAN.dbf / DC2732A_CAN.dbc for
scaling factors and units.
All current dependent measurement quantities have to be
scaled with 1/R
SNS
, where R
SNS
is the resistance of the
shunt resistor.
Example ACC_C1/ACC_E1:
The scaling factors and units from the .dbc file are:
BO_ 293 ACC_C1: 6 Vector__XXX
SG_ C1 : 7|48@0- (0.377887,0)
[-5.013|5.013] “uVms”
Vector__XXX
BO_ 294 ACC_E1: 6 Vector__XXX
SG_ E1 : 7|48@0- (2.32175,0)
[-3.014|3.014] “uVVms”
Vector__XXX
BO_ 295 ACC_TB1: 4 Vector__XXX
SG_ TB1 : 7|32@0- (0.397777,0)
[-8.5422e+008|8.5422e+008]
“ms”
Vector__XXX
The factors are taken from LTC2949 data sheet:
Table 26.
Accumulated Results Register Parameters for Use with
Crystal or Internal Clock
but scaled for units ms and μV.
Charge is given in microvolts times milliseconds, Energy
is given in microvolts times volts times millisecond. The
conversion to As/Ws in case of a 100μΩ shunt is:
Charge = ACC_C1[uV*ms] / 1e6[uV/V]
/ 1000[ms/s] / 100e-6[Ohms] = ACC_C1 *
1e-5 [Vs/Ohms = As]
Energy = ACC_E1[uV*V*ms] / 1e6[uV/V]
/ 1000[ms/s] / 100e-6[Ohms] = ACC_E1 *
1e-5 [V2 s / Ohm = VAs = Ws]
DC2732A_CAN: LTC2949 CAN FIRMWARE
DC2732A_CAN’s CAN baud rate is set to 500k Bit/s but
may be changed via the Serial monitor.
CAN Messages Overview
The DC2732A_CAN uses CAN messages listed in Table 1.
See also DC2732A_CAN.dbf.