Hello,
I have a similar problem with the new RB433UAHL which is the new version of the 433 without serial port. The serial port is missing and I tried to solder a TTL adaptor to pin GND, TX and RX. Using this approach no data come from the serial port at each reboot, however I noticed that if I try a netboot with a custom NAND initramfs openwrt image the serial port starts to emit data, however it hangs before full initialization and the led stops to blink.
I don't have a 711 board but i think that the behaviour could be similar. I notice that the board pass this kernel command line to the initrd:
Kernel command line: GPIO_RESET=yes no-uart gpio=2867 HZ=3400000
00 mem=128M kmac=00:0C:42:ED:73:56 board=433UL boot=0 mlc=2 rootfstype=yaffs noinitrd
in which there is the command no-uart. Also the kernel fails to load because it cannot find the board 433UL. Do you know how i can force a different kernel command line in order to see if forcing it to 433U and removing no-uart line could resolve the issue?
Here is the capture of the serial I receive on boot:
[ 0.000000] bootconsole [early0] enabled
[ 0.000000] CPU revision is: 00019374 (MIPS 24Kc)
[ 0.000000] SoC: Atheros AR7161 rev 2
[ 0.000000] Clocks: CPU:680.000MHz, DDR:340.000MHz, AHB:170.000MHz, Ref:40.00
0MHz
[ 0.000000] Determined physical RAM map:
[ 0.000000] memory: 08000000 @ 00000000 (usable)
[ 0.000000] User-defined physical RAM map:
[ 0.000000] memory: 08000000 @ 00000000 (usable)
[ 0.000000] Initrd not found or empty - disabling initrd
[ 0.000000] Zone ranges:
[ 0.000000] Normal [mem 0x00000000-0x07ffffff]
[ 0.000000] Movable zone start for each node
[ 0.000000] Early memory node ranges
[ 0.000000] node 0: [mem 0x00000000-0x07ffffff]
[ 0.000000] Primary instruction cache 64kB, VIPT, 4-way, linesize 32 bytes.
[ 0.000000] Primary data cache 32kB, 4-way, VIPT, cache aliases, linesize 32
bytes
[ 0.000000] Built 1 zonelists in Zone order, mobility grouping on. Total pag
es: 32512
[ 0.000000] Kernel command line: GPIO_RESET=yes no-uart gpio=2867 HZ=3400000
00 mem=128M kmac=00:0C:42:ED:73:56 board=433UL boot=0 mlc=2 rootfstype=yaffs noi
nitrd
[ 0.000000] MIPS: no machine found for id '433UL', supported machines:
[ 0.000000] id name
[ 0.000000] Generic Generic AR71XX/AR724X/AR913X based board
[ 0.000000] ALFA-AP96 ALFA Network AP96
[ 0.000000] ALFA-NX ALFA Network N2/N5
[ 0.000000] ALL0258N Allnet ALL0258N
[ 0.000000] ALL0315N Allnet ALL0315N
[ 0.000000] AP113 Atheros AP113
[ 0.000000] AP121-MINI Atheros AP121-MINI
[ 0.000000] AP121 Atheros AP121 reference board
[ 0.000000] AP136 Atheros AP136 reference board
[ 0.000000] AP81 Atheros AP81 reference board
[ 0.000000] AP83 Atheros AP83
[ 0.000000] AP96 Atheros AP96
[ 0.000000] AW-NR580 AzureWave AW-NR580
[ 0.000000] CAP4200AG Senao CAP4200AG
[ 0.000000] DB120 Atheros DB120 reference board
[ 0.000000] DIR-615-E4 D-Link DIR-615 rev. E4
[ 0.000000] DIR-600-A1 D-Link DIR-600 rev. A1
[ 0.000000] DIR-615-C1 D-Link DIR-615 rev. C1
[ 0.000000] DIR-825-B1 D-Link DIR-825 rev. B1
[ 0.000000] EW-DORIN-ROUTER EmbWir-Dorin-Router
[ 0.000000] EW-DORIN EmbWir-Dorin
[ 0.000000] ALL0305 Allnet ALL0305
[ 0.000000] EAP7660D Senao EAP7660D
[ 0.000000] JA76PF2 jjPlus JA76PF2
[ 0.000000] JA76PF jjPlus JA76PF
[ 0.000000] JWAP003 jjPlus JWAP003
[ 0.000000] HORNET-UB ALFA NETWORKS Hornet-UB
[ 0.000000] MR600 OpenMesh MR600
[ 0.000000] MZK-W04NU Planex MZK-W04NU
[ 0.000000] MZK-W300NH Planex MZK-W300NH
[ 0.000000] NBG460N Zyxel NBG460N/550N/550NH
[ 0.000000] OM2P-HS OpenMesh OM2P HS
[ 0.000000] OM2P-LC OpenMesh OM2P LC
[ 0.000000] OM2P OpenMesh OM2P
[ 0.000000] PB42 Atheros PB42
[ 0.000000] PB44 Atheros PB44 reference board
[ 0.000000] PB92 Atheros PB92
[ 0.000000] 493G MikroTik RouterBOARD 493G
[ 0.000000] 493 MikroTik RouterBOARD 493/AH
[ 0.000000] 450G MikroTik RouterBOARD 450G
[ 0.000000] 450 MikroTik RouterBOARD 450
[ 0.000000] 435G MikroTik RouterBOARD 435G
[ 0.000000] 433U MikroTik RouterBOARD 433UAH
[ 0.000000] 433 MikroTik RouterBOARD 433/AH
[ 0.000000] 411U MikroTik RouterBOARD 411U
[ 0.000000] 411 MikroTik RouterBOARD 411/A/AH
[ 0.000000] 751g MikroTik RouterBOARD 751G
[ 0.000000] 751 MikroTik RouterBOARD 751
[ 0.000000] 750Gr3 MikroTik RouterBOARD 750GL
[ 0.000000] 750i MikroTik RouterBOARD 750
[ 0.000000] 2011G MikroTik RouterBOARD 2011UAS-2HnD
[ 0.000000] 2011L MikroTik RouterBOARD 2011L
[ 0.000000] RW2458N Redwave RW2458N
[ 0.000000] TEW-632BRP TRENDnet TEW-632BRP
[ 0.000000] TEW-673GRU TRENDnet TEW-673GRU
[ 0.000000] TEW-712BR TRENDnet TEW-712BR
[ 0.000000] TL-MR3040 TP-LINK TL-MR3040
[ 0.000000] TL-MR11U TP-LINK TL-MR11U
[ 0.000000] TL-MR3020 TP-LINK TL-MR3020
[ 0.000000] TL-WR841N-v7 TP-LINK TL-WR841N/ND v7
[ 0.000000] TL-MR3420 TP-LINK TL-MR3420
[ 0.000000] TL-MR3220 TP-LINK TL-MR3220
[ 0.000000] TL-WA7510N TP-LINK TL-WA7510N v1
[ 0.000000] TL-WA901ND TP-LINK TL-WA901ND
[ 0.000000] TL-WA901ND-v2 TP-LINK TL-WA901ND v2
[ 0.000000] TL-WDR4300 TP-LINK TL-WDR3600/4300/4310
[ 0.000000] TL-WR741ND TP-LINK TL-WR741ND
[ 0.000000] TL-WR741ND-v4 TP-LINK TL-WR741ND v4
[ 0.000000] TL-WR841N-v1.5 TP-LINK TL-WR841N v1
[ 0.000000] TL-WR841N-v8 TP-LINK TL-WR841N/ND v8
[ 0.000000] TL-WR941ND TP-LINK TL-WR941ND
[ 0.000000] TL-WR1041N-v2 TP-LINK TL-WR1041N v2
[ 0.000000] TL-WR1043ND TP-LINK TL-WR1043ND
[ 0.000000] TL-WR2543N TP-LINK TL-WR2543N/ND
[ 0.000000] TL-WR703N TP-LINK TL-WR703N v1
[ 0.000000] UBNT-LS-SR71 Ubiquiti LS-SR71
[ 0.000000] UBNT-LSX Ubiquiti LSX
[ 0.000000] UBNT-RSPRO Ubiquiti RouterStation Pro
[ 0.000000] UBNT-RS Ubiquiti RouterStation
[ 0.000000] UAP-PRO Ubiquiti UniFi AP Pro
[ 0.000000] UBNT-U20 Ubiquiti UniFiAP Outdoor
[ 0.000000] UBNT-UF Ubiquiti UniFi
[ 0.000000] UBNT-AR Ubiquiti AirRouter
[ 0.000000] UBNT-NM Ubiquiti Nanostation M
[ 0.000000] UBNT-RM Ubiquiti Rocket M
[ 0.000000] UBNT-BM Ubiquiti Bullet M
[ 0.000000] UBNT-XM Ubiquiti Networks XM (rev 1.0) board
[ 0.000000] WHR-HP-GN Buffalo WHR-HP-GN
[ 0.000000] WHR-G301N Buffalo WHR-G301N
[ 0.000000] WHR-HP-G300N Buffalo WHR-HP-G300N
[ 0.000000] WLAE-AG300N Buffalo WLAE-AG300N
[ 0.000000] WNDR3700 NETGEAR WNDR3700/WNDR3800/WNDRMAC
[ 0.000000] WNDR4300 NETGEAR WNDR4300
[ 0.000000] WNR2000 NETGEAR WNR2000
[ 0.000000] WP543 Compex WP543
[ 0.000000] WPE72 Compex WPE72
[ 0.000000] WRT160NL Linksys WRT160NL
[ 0.000000] WRT400N Linksys WRT400N
[ 0.000000] WZR-HP-G300NH Buffalo WZR-HP-G300NH
[ 0.000000] WZR-HP-G300NH2 Buffalo WZR-HP-G300NH2
[ 0.000000] WZR-HP-AG300H Buffalo WZR-HP-AG300H
[ 0.000000] WZR-HP-G450H Buffalo WZR-HP-G450H
[ 0.000000] ZCN-1523H-5 Zcomax ZCN-1523H-5
[ 0.000000] ZCN-1523H-2 Zcomax ZCN-1523H-2
[ 0.000000] PID hash table entries: 512 (order: -1, 2048 bytes)
[ 0.000000] Dentry cache hash table entries: 16384 (order: 4, 65536 bytes)
[ 0.000000] Inode-cache hash table entries: 8192 (order: 3, 32768 bytes)
[ 0.000000] __ex_table already sorted, skipping sort
[ 0.000000] Writing ErrCtl register=00059090
[ 0.000000] Readback ErrCtl register=00059090
[ 0.000000] Memory: 124548k/131072k available (2093k kernel code, 6524k reser
ved, 407k data, 2260k init, 0k highmem)
[ 0.000000] SLUB: Genslabs=9, HWalign=32, Order=0-3, MinObjects=0, CPUs=1, No
des=1
[ 0.000000] NR_IRQS:51
[ 0.000000] Calibrating delay loop... 452.19 BogoMIPS (lpj=2260992)
[ 0.060000] pid_max: default: 32768 minimum: 301
[ 0.060000] Mount-cache hash table entries: 512
[ 0.070000] NET: Registered protocol family 16
[ 0.070000] MIPS: machine is Generic AR71XX/AR724X/AR913X based board
[ 0.080000] bio: create slab <bio-0> at 0
[ 0.090000] Switching to clocksource MIPS
[ 0.090000] NET: Registered protocol family 2
[ 0.100000] TCP established hash table entries: 4096 (order: 3, 32768 bytes)
[ 0.100000] TCP bind hash table entries: 4096 (order: 2, 16384 bytes)
[ 0.110000] TCP: Hash tables configured (established 4096 bind 4096)
[ 0.110000] TCP: reno registered
[ 0.120000] UDP hash table entries: 256 (order: 0, 4096 bytes)
[ 0.120000] UDP-Lite hash table entries: 256 (order: 0, 4096 bytes)
[ 0.130000] NET: Registered protocol family 1
[ 2.570000] msgmni has been set to 243
[ 2.580000] io scheduler noop registered
[ 2.580000] io scheduler deadline registered (default)
[ 2.590000] Serial: 8250/16550 driver, 1 ports, IRQ sharing disabled
[ 2.610000] serial8250.0: ttyS0 at MMIO 0x18020000 (irq = 11) is a 16550A