Differences

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--- spark_counter [2015/12/07 15:36] – add Orange Pi kingkevin
+++ spark_counter [2015/12/28 10:26] – [peacefair PZEM-004] kingkevin
@@ Line 37: / Line 37: @@
 The meter also provides a UART port to query the measured values.
 Two opto-couplers isolate the main power meter circuits from the TX and RX UART ports.
+^ UART ^ PZEM-004 ^ note ^
+| 5V | VDD | 3.3V is not enough |
+| TX | RX | the UART pin needs to be able to sink ~4 mA |
+| RX | TX | the UART pin needs to be idle high |
+| GND | GND | |
+I used a CP2102 based USB to UART converter.
+CH340 based USB to UART converters will not work (it seems to not be able to sink enough current).
+And when using the Arduino you should not use the USB port (for serial), since that interferes with the UART signals.
 The {{:spark_counter:pzem-004.rtf|manual}} provides the corresponding commands, but lacks some information.
@@ Line 137: / Line 147: @@
 The values are then simply stored in an [[https://influxdb.com/|InfluxDB]] time series database for visualisation in [[http://grafana.org/|grafana]].
+Note: there is no ARM build of grafana (armel for RPi 1, armhf for later versions).
+This is also because there is no ARM release of [[http://phantomjs.org/|PhantomJS]].
+I'm running grafana on my local computer (amd64), using the remote database on the RPi.
 {{:spark_counter:grafana.png?0x200|grafana visualization}}
 ====== Orange Pi ======
-There is no armel build of grafana for the Raspberry Pi, and compiling it from source wasn't possible because 256MB of RAM aren't enough.
-Thus I tried to use a Orange Pi since it was also lying around.
 The [[http://www.orangepi.org/orangepipc/|Orange Pi PC]] is a cheap [[http://www.aliexpress.com/item/Orange-Pi-PC-ubuntu-linux-and-android-mini-PC-Beyond-and-Compatible-with-Raspberry-Pi-2/32448079125.html|$15 alternative]] to the Raspberry Pi 2.
-This single board computer is based on an [[https://linux-sunxi.org/H3|Allwinner H3 (sun8iw7p1)]] SoC with ARM Cortex-A7 @ 1.8GHz, and 1 GB of RAM.
+This single board computer is based on an [[https://linux-sunxi.org/H3|Allwinner H3 (sun8iw7p1)]] SoC with ARM Cortex-A7 @ 1.2GHz (often over-clocked), and 1 GB of RAM.
-That should be plenty to compile and run grafana.
-For this price the hardware is unbeatable, but the software support is quite poor (outdated but indicating [[http://www.orangepi.org/Docs/FAQ.html|FAQ]]).
+For this price the hardware is unbeatable, but the software support is really poor.
-Only Android supports the video hardware acceleration currently.
+Also only Android supports the video hardware acceleration currently.
-The official [[http://www.orangepi.org/downloadresources/|images]] are old (e.g. Android 4.2.2), but there are newer images made available by the community:
+The official [[http://www.orangepi.org/downloadresources/|images]] are quite old (e.g. Android 4.2.2), but there are a bit newer images made available by the community:
-  * such as [[http://www.orangepi.org/orangepibbsen/forum.php?mod=viewthread&tid=755|Android]], with weird [[http://www.orangepi.org/Docs/SDcardinstallation.html#Install_Android_OS_image|installation process]]
+  * [[http://www.orangepi.org/orangepibbsen/forum.php?mod=viewthread&tid=755|Android]] (often ROMs from other Allwinner based products), with a weird [[http://www.orangepi.org/Docs/SDcardinstallation.html#Install_Android_OS_image|installation process]]
-  * various [[http://www.orangepi.org/orangepibbsen/forum.php?mod=viewthread&tid=342|linux]]
+  * various [[http://www.orangepi.org/orangepibbsen/forum.php?mod=viewthread&tid=342|linux]] distributions
 Since I'll only use it as server I decided to go with debian jessie minimal.
 The pin header is the same as the [[http://www.raspberry-projects.com/pi/pi-hardware/raspberry-pi-2-model-b/rpi2-model-b-io-pins|40-pin Raspberry Pi]].