alirezasalehy / plnic

This repository contains resources of plNIC project using KQ-130F as Power Line Modem (PLM) and STM32F030C8T6 as plNIC's MCU. The driver for plNIC is written in C#.

plNIC using KQ130F FSK modem

The under developed plNIC will provide encryption, DMA, buffering techniques, CRC error checking and RTOS(FreeRTOS).

Hardware

KQ130-F

This PLM has fairly simple application and interface circuit, Though it is not provided with enough and clear documentations. Here is the pinout: As it's shown; there is 9 pins in total and that pins 1 and 2 are connected to AC powerline(No matter you connect phase wire or neutral wire to pin 1 or 2), pins 3, 4 and 5 provides power and pin 6 and 7 are used for data communication.

The figure above shows connections for AT89C51 MCU which uses TTL logic level. Remember that this PLM suppots TTL logical voltage levels so you need a voltage devider if you want to use it with a 3.3v MCU like STM32 MCUs. I used Resistor Voltage Devider to convert 5v TTL to 3.3v in MCU rx <-> KQ130-F tx connection. However there is no need to do so for MCU tx <-> KQ130-F rx. Resistor voltage devider is suitable for this application because baud rate of data signals are relatively very low. Otherwise we might need to use diode or FET based voltage converters or rather to use converter chips like this.

STM32F030C8

DMA

CRC

UART

Schematic

The designed schematic of plNIC is shown bellow:

Note Due to Hi-Z state of pins, if using pin headers and detachable connections in my implementation of this schema, I recommend using a pull-up resistor on the base pin of transistors. So to pull the base pin to a logical one by default.

Bill of Materials

BOM for every plNIC is as follows:

Reference	Value	Footprint	Qty
C1, C2	10pF		2
C4	10uF		1
C3, C5, C7	0.1uF		3
C9	10nF		1
C10	4.7uF		1
C8, C13	100nF		2
C6, C15	1uF		2
D1	YELLOW		1
D2	GREEN		1
D3	RED		1
D4	1N4001	Diode_THT:D_DO-41_SOD81_P10.16mm_Horizontal	1
J1	Screw_Terminal_01x02		1
J3	UART_DEBUG		1
J4	SW_DEBUG		1
J5	plNIC Interface		1
JP1	Jumper		1
Q1, Q2	BC327	Package_TO_SOT_THT:TO-92_Inline	2
R1, R2	10k		2
R3	1k		1
R4	2k		1
R5, R6	150		2
R7	330		1
R8, R9	3K2		2
SW1	SW_Push		1
TH1	800mA PTC		1
U1	STM32F030C8Tx	Package_QFP:LQFP-48_7x7mm_P0.5mm	1
U2	LF33_TO220	Package_TO_SOT_THT:TO-220-3_Vertical	1
U3	LM7805_TO220	Package_TO_SOT_THT:TO-220-3_Vertical	1
U4	KQ130-F		1
Y1	32.768Hz		1

Implementation Specific parts:

Reference	Value	Footprint	Qty
Hole Board	9cm * 7cm double sided		1
SMD to DIP	QFN48 to DIP package converter		1

Implemented Module

The discussed plNIC soldered on double sided hole board as bellow:

Warning Although the datasheet states that leaving MODE pin in Hi-Z is fine, I suggest you not to do this. Using Custom mode and pulling the pin to the ground is a much better approach. After mentioned adjustment two awkward problems encountered were solved. Which were noisy transmissions and power supply problem.

Warning The ambiguous insufficient documentation of this Chinese modem, which I provided in Docs/Texts, states that the maximum current crossing the modem is about 300mA. Though my tests reveal effectively more current passing it. This misinformation made me use a heat sink after board soldering, which was a trouble, as it gets necessary. So be careful about it.

Note This website has useful information to calculate Total Thermal Resistance(θ_JA(TOTAL)) and need of heat sink: https://www.petervis.com/electronics/Voltage_Regulator_Heatsink/Heatsink_for_TO-220_Voltage_Regulator.html

Final Version

Based on the above explanation, version 1.4 of plNIC board designed and looks like this:

Note There is also another neat approach to this problem. The problem should get solved by using multiple (2 should be enough) LM7805 regulators in parallel to supply current to this current beast. (However I've not tested, It is a more promising solution because you should not need heat sinks and can lower the input voltage, as well)

Software