Analysis done by Denis Kalashnikov:
It seems that some ROS versions on some routerboard models have this bug:
after silence boot (no output to uart, no beeps) beeper clicks when wireless traffic is.
https://forum.mikrotik.com/viewtopic.php?f=3&t=92269https://forum.mikrotik.com/viewtopic.php?t=63399
From these links:
1)
Hello, I have RB951G-2HnD and I noticed strange thing
when I loaded the device with some wireless traffic it
produced strange sound - like hissing, fizzing etc.
2)
Same problem still on 6.33, with silent boot enabled
I hear buzzing noise on wireless load.
3)
The sound is fixed in v5.19, it was a bug that caused beeper to make clicks.
It also got fixed in RouterOS:
* What's new in 5.19 (2012-Jul-16 10:51):
fix ticking sound on RB411UAHL;
* What's new in 6.38.3 (2017-Feb-07 09:52):
rb3011 - fixed noise from buzzer after silent boot;
I've checked with an oscilloscope that:
* When on the ssr beeper pin is 0,
on the beeper itself is 1 (~5V),
and when on the ssr beeper pin is 1,
on the beeper is 0
The beeper doesn't consume power,
so 1 should be a default/idle value for the ssr beeper pin).
* When there is wireless traffic (ping packets)
in the background and the beeper clicks, I see
pulses on the beeper itself,
but no pulses on the ssr beeper pin (Q5 pin of 74hc595).
When I manually toggle the ssr beeper pin I see pulses on both.
So, it is likely that the phantom beeper clicks are caused by the EMI.
Suggested-by: Denis Kalashnikov <denis281089@gmail.com>
Reviewed-by: Sergey Ryazanov <ryazanov.s.a@gmail.com>
Signed-off-by: Koen Vandeputte <koen.vandeputte@ncentric.com>
This board has been supported in the ar71xx.
Links:
* https://mikrotik.com/product/RB912UAG-2HPnD
* https://openwrt.org/toh/hwdata/mikrotik/mikrotik_rb912uag-2hpnd
This also supports the 5GHz flavour of the board.
Hardware:
* SoC: Atheros AR9342,
* RAM: DDR 64MB,
* SPI NOR: 64KB,
* NAND: 128MB,
* Ethernet: x1 10/100/1000 port with passive POE in,
* Wi-Fi: 802.11 b/g/n,
* PCIe,
* USB: 2.0 EHCI controller, connected to mPCIe slot and a Type-A
port -- both can be used for LTE modem, but only one can be
used at any time.
* LEDs: 5 general purpose LEDs (led1..led5), power LED, user LED,
Ethernet phy LED,
* Button,
* Beeper.
Not working:
* Button: it shares gpio line 15 with NAND ALE and NAND IO7,
and current drivers doesn't easily support this configuration,
* Beeper: it is connected to bit 5 of a serial shift register
(tested with sysfs led trigger timer). But kmod-gpio-beeper
doesn't work -- we left this as is for now.
Flashing:
* Use the RouterBOARD Reset button to enable TFTP netboot,
boot kernel and initramfs and then perform sysupgrade.
* From ar71xx OpenWrt firmware run:
$ sysupgrade -F /tmp/<sysupgrade.bin>
For more info see: https://openwrt.org/toh/mikrotik/common.
Co-Developed-by: Koen Vandeputte <koen.vandeputte@citymesh.com>
Reviewed-by: Sergey Ryazanov <ryazanov.s.a@gmail.com>
Signed-off-by: Denis Kalashnikov <denis281089@gmail.com>
