Thread: Garmin eTREX 20 working as an eTREX 30

Hello, we have done some testing with three possible values to write in 0x40014D4, ​​1, 3 and 5. These values ​​can also be 2 and 4.
I think 1, 3 and 5 are for etrex30. and the values ​​for models 2 and 4 etrex20
I believe that these values ​​may correspond to different versions of the same model PCB etrex20.
In my gps etrex20:
1 - white screen. But it seems to work the gps.
2 - Gps eTREX20 mode operating normally
3 - normal operation mode Gps eTREX30 (not sensors: barometer, compass, ant+, add some menus)
4 - Not tested
5 - white screen. But it seems to work the gps.

In another gps eTREX20 of other forum:
1 - white screen. But it seems to work the gps.
2 - white screen. But it seems to work the gps.
3 - white screen. But it seems to work the gps.
4 - Gps eTREX20 mode operating normally
5 - normal operation mode Gps eTREX30 (not sensors: barometer, compass, ant+, add some menus)


In the absence of further evidence, is what we can conclude.

GRMFW:80203732 sub_80203732 ; CODE XREF: sub_802037B8+1Cp
GRMFW:80203732 LDR R0, =0x12009000
GRMFW:80203734 PUSH {R4,LR}
GRMFW:80203736 LDR R3, =0x40014D4
GRMFW:80203738 LDR R2, [R0,#0x20]
GRMFW:8020373A MOVS R1, 0x1E0000
GRMFW:8020373E ORRS R2, R1
GRMFW:80203740 STR R2, [R0,#0x20]
GRMFW:80203742 LDR R2, [R0,#0x24]
GRMFW:80203744 BICS R2, R1
GRMFW:80203746 STR R2, [R0,#0x24]
GRMFW:80203748 LDR R0, [R0]
GRMFW:8020374A LSLS R0, R0, #0xB ;r0*0x800 ?
GRMFW:8020374C LSRS R0, R0, #0x1C ;r0/0x1000000 ?
GRMFW:8020374E STRB R0, [R3]
GRMFW:80203750 LDRB R0, [R3]
GRMFW:80203752 STRB R0, [R3,#1]
GRMFW:80203754 BL sub_80200AD0
GRMFW:80203758 POP {R4,PC}

You could somehow find the bytes that are written to the address 0x12009000, I think that is where you define the motherboard model.?

Leave a link with versions 1, 3 and 5 in case anyone wants to try it. All versions 2.80 with jnx patched eTREX20to30.
Using usb-boot method, by updater.exe.
It's the cleanest way to do the update.
[Only registered and activated users can see links. ]