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authorKoen Vandeputte <koen.vandeputte@ncentric.com>2021-06-28 10:57:21 +0200
committerKoen Vandeputte <koen.vandeputte@ncentric.com>2021-07-01 11:58:36 +0200
commita58bcc9e673db3c6aa39f2089d216d51c8356418 (patch)
tree976c99188b53eca516f6b4a9c7354f25b7bd45ce /target/linux/ath79
parent964863bb23999a1fae99b883053cc4f3c5c42b40 (diff)
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ath79: mikrotik: fix beeper phantom noise on RB912
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=92269 https://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>
Diffstat (limited to 'target/linux/ath79')
-rw-r--r--target/linux/ath79/dts/ar9342_mikrotik_routerboard-912uag-2hpnd.dts6
1 files changed, 6 insertions, 0 deletions
diff --git a/target/linux/ath79/dts/ar9342_mikrotik_routerboard-912uag-2hpnd.dts b/target/linux/ath79/dts/ar9342_mikrotik_routerboard-912uag-2hpnd.dts
index cc5553acda..ee2c12b4e0 100644
--- a/target/linux/ath79/dts/ar9342_mikrotik_routerboard-912uag-2hpnd.dts
+++ b/target/linux/ath79/dts/ar9342_mikrotik_routerboard-912uag-2hpnd.dts
@@ -107,6 +107,12 @@
gpio-export {
compatible = "gpio-export";
+ beeper {
+ gpio-export,name = "beeper";
+ gpio-export,output = <1>; /* Must be 1 to avoid EMI induced clicking noise */
+ gpios = <&ssr 5 GPIO_ACTIVE_HIGH>;
+ };
+
usb_power {
gpio-export,name = "power-usb";
gpio-export,output = <1>;