Thread: Garmin eTREX 20 working as an eTREX 30

Firmware version 3.30 is out.

Hoping you can mod this one without too much trouble as this one seems to have fixed the slow stop issue.

Once again how do you load this being a noob at this and is there a danger you can brick the Etrex 20?

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. ]

Update required gentlemen...