View source for Nano 4G

{{DISPLAYTITLE:iPod nano (4th generation)}}
[[Image:nano_4g_frt_a.png|500px]]
[[Image:nano_4g_bck_a.png|500px]]
==Components==
{| class="wikitable"
! Label !! Component !! Part !! Markings !! Notes
|-
| 2
| CPU
| Samsung S5L8720
| 339S0049 ARM, K4X56323PI-KGC4, YWE025QH 825, APL0278A00, N1B2HOP 0831
| ARM1176JZF-S processor. It is definitely worth knowing that this is the exact same processor used in the iTouch 2G. This could mean that some of the same exploits for that could possibly be used. [http://theiphonewiki.com/wiki/index.php?title=S5L8720_(Hardware) Here] is a very interesting page about the S5L8720 processor.
|-
| 
| SDRAM
| 
|
| 32MB, probably MDDR. Integrated into the processor, similar to the iPod Touch and iPhone lines.
|-
| 4
| Accelerometer
| [http://www.st.com/stonline/products/literature/ds/12726.pdf LIS302DL]
| 33DL, 2827
| The newer Touch's, iPhone's, and even the iPad have similar accelerometers, and I've discovered a pattern in the chip names.
|-
| 6
| NAND Flash
| Varies
| TH58NVG6D1DLA87, U20516, JAPAN, 0826MAE
|
|-
| 5
| Audio codec
| [http://www.cirrus.com/en/pubs/proDatasheet/CS42L55_F1.pdf CS42L58]
| 338S055C, 189N0824, SGP
| I determined this because the [[Nano 5G]] has a similar chip, which we are sure of the identity. One person lifted this chip and found that the pins connect to the LCD connector. Not much info was given, and it could just be a common ground, but the identity of this chip is still up in the air.
|-
| 1
| Power manager
| Dialog D1759
| 338S0687-AC, 08288HBB
| 
|-
| 3
| 
| 
|
| 
|}

== Bootrom ==

See [[S5L8720 Bootrom]]. Different from the S5L8720 bootrom used in the iPod Touch 2G (which is iBoot-based, a.k.a. SecureROM).

== Memory Map ==

See [https://www.theiphonewiki.com/wiki/S5L8720_(Hardware)] and [https://code.google.com/archive/p/chronicdev/wikis/N72APDevTree.wiki].

In addition to the above, a few extra memory regions have been found while reverse engineering the [[S5L8720 Bootrom]]:

{| class="wikitable"
! Name !! Address !! Notes
|-
| Mystery DMA
| 0x3880_0000
| A PL080-like DMA engine, but with slightly different MMIO register structure. Used by the [[S5L8720 Bootrom|bootrom]] to copy the DFU payload from 0x2200_0600 to 0x2200_0000 after decryption and verification. Or maybe that's actually doing the decryption? To be investigated.
|-
| Mystery Interrupt Thing
| 0x39a0_0000
| Not the VICs (0x38e0_0000, 0x38e0_1000), not the EdgeIC (0x38e0_2000). Seems to hold 7 different 32-bit registers for interrupt status at 0xa0, and 7 different 32-bit registers for interrupt mask at 0xc0. The 7 different registers correspond to 7 'modes' of ISRs set up in the bootrom. Not much is known about what it does, and what these 'modes' are. To be investigated.
|}

==Reverse Engineering Results==
Timers: These clockgates have been found to be related to timers: 37, 55, 56, 57, 58, 59, 60, 69, 70, 128, 129, 130, 131, 132, 133, 134, 150 and 151.

==Status registers==
We dumped all c0 coprocessor registers:

===c0,c0===
'''Value:''' 0x410FB764

'''Interpretation:''' ARM1176 rev. 4
===c0,c1===
'''Value:''' 0x1D152152

'''Interpretation:''' DCache/ICache 16KB each, 4 way associative, 32 bytes line size
===c0,c2===
'''Value:''' 0x00000000

'''Interpretation:''' No TCM
===c0,c3===
'''Value:''' 0x00000800

'''Interpretation:''' Unified TLB, 8 lockable entries
===c1,c0===
'''Value:''' 0x00000111

'''Interpretation:''' ARM/Thumb1/Jazelle support, no Thumb2 support
===c1,c1===
'''Value:''' 0x00000011

'''Interpretation:''' Trustzone v1
===c1,c2===
'''Value:''' 0x00000033

'''Interpretation:''' Supports debug model v6.1, both applications processor and secure
===c1,c3===
'''Value:''' 0x00000000

'''Interpretation:''' No auxiliary features
===c1,c4===
'''Value:''' 0x01130003

'''Interpretation:''' FCSE, Auxiliary Control register, ARMv6 TCM/DMA, no DMA cache coherency, no multicore cache coherency, VMSA v7
===c1,c5===

'''Value:''' 0x10030302

'''Interpretation:''' Branch target buffer, Harvard architecture, various cache operations supported (see TRM)
===c1,c6===

'''Value:''' 0x01222100

'''Interpretation:''' WFI, Data synchronization barrier, Prefetch flush, Data memory barrier, various TLB/cache operations supported (see TRM), no prefetch cache range operation

===c1,c7===
'''Value:''' 0x00000000

'''Interpretation:''' No hierarchical cache maintenance support
===c2,c0===
'''Value:''' 0x00140011

'''Interpretation:''' Supports BKPT, CDP, CDP2, LDC, LDC2, MCD, MCD2, MRC, MRC2, STC, STC2, MCRR, MCRR2, MRRC, MRRC2, CLZ, SWP and SWPB, doesn't support division, combined compare and branch or bitfield instructions
===c2,c1===
'''Value:''' 0x12002111

'''Interpretation:''' Supports BXJ, BX, BLX, PC loads have BX behavior, supports SXTB, SXTAB, SXTB16, SXTAB16, SXTH, SXTAH, UXTB, 
UXTAB, UXTB16, UXTAB16, UXTH, UXTAH, SRS, RFE, CPS, LDM(2), LDM(3), STM(2) and SETEND
===c2,c2===
'''Value:''' 0x11231121

'''Interpretation:''' Supports REV, REV16, REVSH, MRS, MSR, UMULL, UMLAL, UMAAL, SMULL, SMLAL, SMLABB, SMLABT, SMLALBB, SMLALBT, SMLALTB, SMLALTT, SMLATB, SMLATT, SMLAWB, SMLAWT, SMULBB, SMULBT, SMULTB, SMULTT, SMULWB, SMULWT, SMLAD, SMLADX, SMLALD, SMLALDX, SMLSD, SMLSDX, SMLSLD, SMLSLDX, SMMLA, SMMLAR, SMMLS, SMMLSR, SMMUL, SMMULR, SMUAD, SMUADX, SMUSD, SMUSDX, MLA, restartable LDM/STM, PLD, LDRD, STRD and Q bit in PSRs
===c2,c3===
'''Value:''' 0x01102131

'''Interpretation:''' Supports true NOP, Thumb MOV(3)/CPU, LDREX, STREX, LDREXB, LDREXH, LDREXD, STREXB, STREXH, STREXD, CLREX, SVC, PKHBT, PKHTB, QADD16, QADD8, QADDSUBX, QSUB16, QSUB8, QSUBADDX, SADD16, SADD8, SADDSUBX, SEL, SHADD16, SHADD8, SHADDSUBX, SHSUB16, SHSUB8, SHSUBADDX, SSAT, SSAT16, SSUB16, SSUB8, SSUBADDX, SXTAB16, SXTB16, UADD16, UADD8, UADDSUBX, UHADD16, UHADD8, UHADDSUBX, UHSUB16, UHSUB8, UHSUBADDX, UQADD16, UQADD8, UQADDSUBX, UQSUB16, UQSUB8, UQSUBADDX, USAD8, USADA8, USAT, USAT16, USUB16, USUB8, USUBADDX, UXTAB16, UXTB16, QADD, QDADD, QDSUB, QSUB, and the Q and GE[3:0] bits in the PSRs. Does nut support branch table and Thumb2 instructions.
===c2,c4===
'''Value:''' 0x00001141

'''Interpretation:''' Supports SMC, writeback instructions, shift of loads and stores by 0-3 bits to the left, constant shift options, register controlled shift options, LDRBT, LDRT, STRBT and STRT. No barrier instructions support.
===c2,c5===
'''Value:''' 0x00000000

'''Interpretation:''' No additional implementation defined instruction set extensions

==Helpful pages==
Teardowns:
*http://www.ifixit.com/Guide/First-Look/iPod-Nano-4th-Generation/584/1
Other:
*http://theiphonewiki.com/wiki/index.php?title=S5L8720_(Hardware)