Differences

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--- spark_counter [2015/12/08 16:29] – [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.