[Hardware Hacking General] AdamOutler:
I just wanted to verify Arduino works as an interpreter as well as any other device. I'm documenting it here for anyone who wants to follow and help.

Device setup:

terminal in and type

su
mknod /dev/ttySAC2 c 204 66

Physical setup: 150kohm resistor connected between Pin 4 and 5 on USB. 2 wires connected from the phone's USB pin 2 and 3 to TX1 and RX1 on Arduino.

note: power and ground are not connected and are not required to observe the log below... However once communications stops, randomness will occur at a high rate of speed.

This is the sketch running on the Arduino ATMega processor

void setup() {
// initialize both serial ports:
Serial.begin(115200);
Serial1.begin(115200);
}

void loop() {
// read from port 1, send to port 0:
if (Serial1.available()) {
int inByte = Serial1.read();
Serial.print(inByte, BYTE);
}
// read from port 0, send to port 1:
if (Serial.available()) {
int inByte = Serial.read();
Serial1.print(inByte, BYTE);
}
}

This will produce the readable output when using minicom to connect to ttyUSB0

1
-----------------------------------------------------------
Samsung Primitive Bootloader (PBL) v3.0
Copyright (C) Samsung Electronics Co., Ltd. 2006-2010
-----------------------------------------------------------

+n1stVPN 2688
+nPgsPerBlk 64
+n1stVPN 3008
+nPgsPerBlk 64
PBL found bootable SBL: Partition(4).

Set cpu clk. from 400MHz to 800MHz.
OM=0x9, device=OnenandMux(Audi)
IROM e-fused - Non Secure Boot Version.

-----------------------------------------------------------
Samsung Secondary Bootloader (SBL) v3.0
Copyright (C) Samsung Electronics Co., Ltd. 2006-2010

Board Name: ARIES REV 03
Build On: Sep 21 2010 18:43:18
-----------------------------------------------------------

Re_partition: magic code(0x0)
[PAM: ] ++FSR_PAM_Init
[PAM: ] OneNAND physical base address : 0xb0000000
[PAM: ] OneNAND virtual base address : 0xb0000000
[PAM: ] OneNAND nMID=0xec : nDID=0x50
[PAM: ] --FSR_PAM_Init
fsr_bml_load_partition: pi->nNumOfPartEntry = 12
partitions loading success
board partition information update.. source: 0x0
Now Read Images - ID : 1
.Done.
read 1 units.
==== PARTITION INFORMATION ====
ID : IBL+PBL (0x0)
ATTR : RO SLC (0x1002)
FIRST_UNIT : 0
NO_UNITS : 1
===============================
ID : PIT (0x1)
ATTR : RO SLC (0x1002)
FIRST_UNIT : 1
NO_UNITS : 1
===============================
ID : EFS (0x14)
ATTR : RW STL SLC (0x1101)
FIRST_UNIT : 2
NO_UNITS : 40
===============================
ID : SBL (0x3)
ATTR : RO SLC (0x1002)
FIRST_UNIT : 42
NO_UNITS : 5
===============================
ID : SBL2 (0x4)
ATTR : RO SLC (0x1002)
FIRST_UNIT : 47
NO_UNITS : 5
===============================
ID : PARAM (0x15)
ATTR : RW STL SLC (0x1101)
FIRST_UNIT : 52
NO_UNITS : 20
===============================
ID : KERNEL (0x6)
ATTR : RO SLC (0x1002)
FIRST_UNIT : 72
NO_UNITS : 30
===============================
ID : RECOVERY (0x7)
ATTR : RO SLC (0x1002)
FIRST_UNIT : 102
NO_UNITS : 30
===============================
ID : FACTORYFS (0x16)
ATTR : RW STL SLC (0x1101)
FIRST_UNIT : 132
NO_UNITS : 1146
===============================
ID : DBDATAFS (0x17)
ATTR : RW STL SLC (0x1101)
FIRST_UNIT : 1278
NO_UNITS : 536
===============================
ID : CACHE (0x18)
ATTR : RW STL SLC (0x1101)
FIRST_UNIT : 1814
NO_UNITS : 140
===============================
ID : MODEM (0xb)
ATTR : RO SLC (0x1002)
FIRST_UNIT : 1954
NO_UNITS : 50
===============================
loke_init: j4fs_open success..
load_lfs_parameters valid magic code and version.
load_debug_level reading debug level from file successfully(0x574f4c44).
init_fuel_gauge: vcell = 4118mV, soc = 85
check_quick_start_condition- Voltage: 4118.75000, Linearized[85/100/100], Capac8
init_fuel_gauge: vcell = 4113mV, soc = 85, rcomp = d01f
reading nps status file is successfully!.
nps status=0x504d4f43
PMIC_IRQ1 = 0xc0
PMIC_IRQ2 = 0x0
PMIC_IRQ3 = 0x1
PMIC_IRQ4 = 0x0
PMIC_STATUS1 = 0x40
PMIC_STATUS2 = 0x2c
get_debug_level current debug level is 0x574f4c44.
aries_process_platform: Debug Level Low
keypad_scan: key value ----------------->= 0x0
CONFIG_ARIES_REV:48 , CONFIG_ARIES_REV03:48
check_download: micorusb_status1 = 8, key_value = 0
aries_process_platform: final s1 booting mode = 0
DISPLAY_PATH_SEL[MDNIE 0x1]is on
MDNIE setting Init start!!
vsync interrupt is off
video interrupt is off
[fb0] turn on
MDNIE setting Init end!!

Autoboot (0 seconds) in progress, press any key to stop
get_debug_level current debug level is 0x574f4c44.
get_debug_level current debug level is 0x574f4c44.
boot_kernel: Debug Level Low
FOTA Check Bit
Read BML page=, NumPgs=
FOTA Check Bit (0xffffffff)
Load Partion idx = (6)
..............................done
Kernel read success from kernel partition no.6, idx.6.
setting param.serialnr=0x393176a8 0x828e00ec
setting param.board_rev=0x30
setting param.cmdline=console=ttySAC2,115200 loglevel=4

Starting kernel at 0x314dc000...

BOOTING COMPLETED

when booting press and hold enter when communicating over serial to set environmental variables. I will be playing with these to see if I can change OM values here's the defaults

SBL> printenv
PARAM Rev 1.3
SERIAL_SPEED : 7
LOAD_RAMDISK : 0
BOOT_DELAY : 0
LCD_LEVEL : 97
SWITCH_SEL : 65
PHONE_DEBUG_ON : 0
LCD_DIM_LEVEL : 0
LCD_DIM_TIME : 6
MELODY_MODE : 1
REBOOT_MODE : 0
NATION_SEL : 0
LANGUAGE_SEL : 0
SET_DEFAULT_PARAM : 0
PARAM_INT_13 : 0
PARAM_INT_14 : 0
VERSION : I9000XXIL
CMDLINE : console=ttySAC2,115200 loglevel=4
DELTA_LOCATION : /mnt/rsv
PARAM_STR_3 :
PARAM_STR_4 :

This is my dev phone. If anyone has experimental code to be loaded... I'll try it out.