Nornally are ARM processor (ST) in little endian.
The jtag port, someone would have to check.
What do you mean with "Init".
You may DISASSEMBLE almost all firmware and define some functions.
Typically consists of a CPU, a memory Nor (256Mb) and eMMC memory.
The firmware is in memory Nor, structured regions.
bootblock
bootloader
Firmware
nvram
etc. ..

You can see the same pad solders, standard JTAG connector Garmin.
Specifically, this belongs to Garmin etrex20/30.

http://imageshack.com/scaled/large/202/9oe1.jpg Uploaded with ImageShack.us

I can not prove it. Because I have not the easy-jtag box.
I'm negotiating for a shipment to Spain but leaves more than 180 €. I try to get it cheaper, in order to experience the different models of Garmin.

Ok... my number 5 pin is also ground.

I tried to connect as in your picture...then I also connected the others and tried for " Jtag pinout finder" ..it didn't work non were detected.
But even if we have the pinout ...if we do not have an init script you cannot connect to it.

Hello, to identify the port jtag not need any init.
You should locate the ID of the CPU.

I think the probem may be the lack of some component (pull-up resistors etc. ..).
If you look at the picture I posted, lack multiple resistance, which connects several jtag pin to Gnd. After lack a capacitor and a resistor that will Vcc.

I'll put the photo jtag port with its components of a test etrex20/30 Garmin.

http://imageshack.com/scaled/medium/198/i76u.jpg Uploaded with ImageShack.us

Here is a photo of a model jtag port Garmin 60csx, where you can see the name of 3 of the pins. Tdi, Tms, Tck.

Maybe someone can help us know if you need to place these resistors, or something similar.

http://imageshack.com/scaled/medium/845/a81a.jpg Uploaded with ImageShack.us

If necessary I can upload a photo more of this connector jtag other garmin GPS model

yes .

Jtag Garmin Nuvi 2x5 (MTK Version)
 

Jtag Garmin Nuvi 2x5 (MTK Version)

Box Working Mode: JTAG Pin Finder.
Starting Z3X Jtag Pin Finder...
Stage 1: Search TCK / TMS / TDI / TDO...
Get IDCODE...
JTAG Pinout Found: TCK: Pin 13 / TMS: Pin 3 / TDI: Pin 5 / TDO: Pin 7
CPU IDCODE : 0x07B76F0F Mfg.: 0x787, Part: 0x7b76, Ver.: 0x0
CPU Manufacturer: Samsung , CPU Name: S3C6410/S5P6422
Stage 2: Searching TRST...
TRST Pin Found: TRST: Pin 9

In Jtag tool:
Warning , you are using <a href="http://easy-jtag.com/?page_id=754">custom pinout config</a> make shure that NRST and GND on proper places!
JTAG Connection is not supported for this device

how can i add this cpu?, i can connec to other models too.
Normally they have a sandisk emmc (SDIN5D2-2G 2GB)
It posible to add read and write emmc byt jtag port?.
Usually almost all garmin gps use CPU ARM7,9 and 11.
Is it possible to configure different sectors in emmc?.

i have a info for sectors of some Garmin gps.

I know it is possible to read the emmc using emmc-tool, but it would be easier for jtag, since the port is the same on almost all Garmin Gps models. So you do not have to look for the emmc points (it usually involves unsoldering the emmc to find them)

Jtag Garmin Nuvi 2x5W
 

Garmin Nuvi nuvi 2x5W

Box Working Mode: JTAG Pin Finder.
Starting Z3X Jtag Pin Finder...
Stage 1: Search TCK / TMS / TDI / TDO...
Get IDCODE...
JTAG Pinout Found: TCK: Pin 7 / TMS: Pin 11 / TDI: Pin 9 / TDO: Pin 5
CPU IDCODE : 0x07926041 Mfg.: 0x020, Part: 0x7926, Ver.: 0x0
Stage 2: Searching TRST...
TRST Pin Found: TRST: Pin 14

Warning , you are using <a href="http://easy-jtag.com/?page_id=754">custom pinout config</a> make shure that NRST and GND on proper places!
JTAG Connection is not supported for this device

it have too, sandisk emmc (SDIN5D2-2G 2GB)

This is another example. It is not supported.

Is there any manual command for jtag, debug, read ram, flash debug, etc ??

Reading emmc sandisk 2GB with jtag isp-adapter (garmin nuvi 2x5 MTK)
 

HiPower mode is off!
SD Card Information
SD CID : 035344534430333280FFFFFFFF0062C4
SD CSD : 40260032515981E9BEF9CFFF92404016
SD Manufacturer ID: 0003 , OEM ID: 5344
SD Date: 02/2006 Rev.0x80
SD NAME: SD032 , S/N: 4294967295
SD NAME (HEX): 53443033322000
SD Capacity: 30 MB
SD Permanent Write Protection: No
SD Temporary Write Protection: No
SD Password Locked: No
Searching for partition tables...
Partitioning not detected...
Done.

easy-jtag only read 30mb, it nos true, and the data is all 0x00

I have read the emmc with a transcend card reader and I could read 2gb, but I can not write. The data read is correct and can verify it.

how i can read and write the entire emmc?

need dump for shv e330s
there is no dump available for this device .....only pinout.....what to doo

chek in nuvi255 dat0 line not corect

Garmin etrex30 reading emmc in board., only read filesystem
 

Garmin etrex 30, it have a emmc 2gb.
It detect and read 1908Mb (but only filesystem region), but it is no de start of the emmc.
the start of emmc is 0x00000000 to 0x02000000
The filesystem start at 0x02000000 to end of emmc.
what is the problem?


Z3X EasyJtag Software ver. 2.5.0.6

Loading eMMC Addon Firmware... IO: 1800 mV
Box S/N: 0D0010228807B87F, ,FW Ver.: 01.58
CMD Pullup Level:1588 mV
CMD Active Level:1753 mV
Box IO Level:1800 mV
CLK Rate:21000 khz
HiPower mode is off!
---------- eMMC Device Information ----------

EMMC CID : 1501004D3247314445101317AABB4F50
EMMC CSD : 900F00320F5A03B9FFFF8FFF96404010
EMMC Manufacturer ID: 0015 , OEM ID: 0100
EMMC Date: 04/2012 Rev.0x10
EMMC NAME: M2G1DE , S/N: 320318139
EMMC NAME (HEX): 4D324731444500
EMMC ROM1 (Main User Data) Capacity: 1908 MB
EMMC ROM2 (Boot Partition 1) Capacity: 0 kB
EMMC ROM3 (Boot Partition 2) Capacity: 0 kB
EMMC RPMB (Replay Protected Memory Block) Capacity: 0 kB
EMMC Permanent Write Protection: No
EMMC Temporary Write Protection: No
EMMC Password Locked: No
Extended CSD rev 1.3 (MMC 4.3)
Boot configuration [PARTITION_CONFIG: 0x00] No boot partition configured.
Boot bus config [177]: 0x00 , width 1bit , Partition config [179]: 0x00.
H/W reset function [RST_N_FUNCTION]: 0x00
High-capacity W protect group size [HC_WP_GRP_SIZE: 0x00000000]
Partitioning Support [PARTITIONING_SUPPORT]: 0x00
Device NOT support partitioning feature
Device cannot have enhanced tech.
Partitioning Setting [PARTITION_SETTING_COMPLETED]: 0x00
---------------------------------------------
Backup saved: M2G1DE_ 320318139_20170201_1844.extcsd
Done.

Z3X EasyJtag Software ver. 2.5.0.6
Skip loading eMMC Addon Firmware
CMD Pullup Level:1588 mV
CMD Active Level:1753 mV
Box IO Level:1800 mV
CLK Rate:21000 khz
Reading 0x000080000000 bytes from 0x000000000000 ...ROM1 ( USER ROM)
Read Length has been corrected to 0x000077400000 bytes...
Output file :D:\Garmin\RAW\etrex20-30\EMMC_ROM1_M2G1DE_320318139_00000000_77400000.bi n
Done. Read Speed: 968 kB/s

https://i.gyazo.com/feedcb6b503eb34c...4efd87f5e4.gif

It seems that the reading is correct and emmc memory is only the region filesystem.
The other regions (x-loader, booot etc.) are in another type of memory

with new soft and firmware 1.58, now read the emmc memory correctly and displays its actual size.
It will have something to do 1.58 Firmware (new IO levels detection).

It is the same memory is the two cases, nothing has been changed, (The memory has always been soldered to the adapter in both cases, has not been touched between test and test).

Good day! With great interest I read this topic, because I'm trying to find a solution to the issue of restoring garmin astro 320. I replaced it with emmc and sta2065, but the navigator does not turn on and does not load into the pre-boot. Did you find the chip in which the boot firmware is stored? Thanks for the reply, colleague!