I performed a learning cycle on bq27421-g1 and then I used the data with the GPC on-line calculator to find the gas gauge's coefficients. I obtained the following from the GPC_report.txt file:
"Optimized Impedance Track Parameters tool, rev=1.25
Optimized Impedance Track parameters:
Qmax, mAh : 270
Ra table normalized to 25C
DOD, % Ra, mOhm
0 124
11.11 124
22.22 310
33.33 326
44.44 183
55.56 162
66.67 326
77.78 345
80.95 296
84.13 246
87.3 274
90.48 502
93.65 989
96.83 1388
100 2212
Ra0_ch, mOhm : 1495 This firmware is not explicitly supporting Ra0_ch, FCC drop could occur at low temperatures if used
Thermal parameters:
T Time Constant 293
T Rise 458
All GG values updated and saved in gg_out.csv , Ra uncompressed , uscaled
0
"
Then I looked at the GG file updated by the tool:
"
Gas Gauging,State,Qmax Cell 0,270,Num
[...]
Ra Tables,R_a RAM,R_a0 0,31,Num
Ra Tables,R_a RAM,R_a0 1,31,Num
Ra Tables,R_a RAM,R_a0 2,77,Num
Ra Tables,R_a RAM,R_a0 3,81,Num
Ra Tables,R_a RAM,R_a0 4,46,Num
Ra Tables,R_a RAM,R_a0 5,41,Num
Ra Tables,R_a RAM,R_a0 6,82,Num
Ra Tables,R_a RAM,R_a0 7,86,Num
Ra Tables,R_a RAM,R_a0 8,74,Num
Ra Tables,R_a RAM,R_a0 9,62,Num
Ra Tables,R_a RAM,R_a0 10,69,Num
Ra Tables,R_a RAM,R_a0 11,126,Num
Ra Tables,R_a RAM,R_a0 12,247,Num
Ra Tables,R_a RAM,R_a0 13,347,Num
Ra Tables,R_a RAM,R_a0 14,553,Num
"
Computing the resistance values for R_a0, for instance, give me:
R_a0 = 31 * 2^-10 = 30.3 mOhm which is inconsistent with the value provided in the GPC_report.txt, which is 124 mOhm. My question is, if I had to set the value of R_a table in the GG file by hand, how to compute the required value from the GPC_report ?
An answer would be greatly appreciated.
