diff --git a/doc/EvseMode.md b/doc/EvseMode.md index 36dde44..3bc1129 100644 --- a/doc/EvseMode.md +++ b/doc/EvseMode.md @@ -76,10 +76,13 @@ Not at the moment. The embedded CCS solutions on ESP32 or STM32 are implementing ### Q8: Which side of the TPlink is the PE and which is the CP? -The TPlink has a RF transformer with 3 coils. Two coils are connected to the modem chip (the transmit and the receive path), and the -third coil is the way to the outside world, in our case the CP and PE. The modulation does not care for the polarity of this path. It uses +The TPlink has a RF transformer with two or three coils. One or two coils are connected to the modem chip (the transmit and the receive path), and the +last coil is the way to the outside world, in our case the CP and PE. The modulation does not care for the polarity of this path. It uses radio frequencies in the range of 2MHz to 30MHz. This means, it does not matter which side of the "outside coil" is connected to PE and which to CP. The only important thing is, that the coil does not connect directly to the CP and PE, because this would destroy the 12V PWM signal, which lives in parallel on the CP / PE lines. The coupling network of 1nF and 150ohms in series assures, that the RF signals and the 12V PWM are not interfering each other. + +The picture shows the two-coil variant: +![image](TPlink_RF_transformer_and_coupling_network.jpg) \ No newline at end of file diff --git a/doc/TPlink_RF_transformer_and_coupling_network.jpg b/doc/TPlink_RF_transformer_and_coupling_network.jpg new file mode 100644 index 0000000..555e664 Binary files /dev/null and b/doc/TPlink_RF_transformer_and_coupling_network.jpg differ