【Training Camp】Light Bar Controller

# Introduction

A light bar touch panel controller based on the Renesas R7FA2E1A72DFL#AA 32-bit series MCU.

### Chip Features

R7FA2E1A72DFL#AA is an entry-level single-chip microcontroller in the RA series, based on a 48 MHz Arm® Cortex®-M23 core, with up to 128 kB of code flash and 16 kB of SRAM. This product uses an optimized process and Renesas Electronics' low-power process technology, and supports a wide operating voltage range of 1.6V to 5.5V and a variety of packages such as LQFP, QFN, LGA, BGA, and WLCSP. The RA2E1 is pin- and peripheral-compatible with the RA2L1 product group, and is particularly suitable for battery-powered applications and space-constrained applications, as well as other systems that require high performance and low power consumption.

* 48MHz Arm® Cortex®-M23;
* 1.6V - 5.5V wide operating voltage range;
* Enhanced capacitive touch sensing unit (CTSU);
* Independent SPI interface / I2C multi-master interface;
* 12-bit ADC, LPACMP, temperature sensor;
* 32-bit general-purpose PWM timer, 16-bit general-purpose PWM timer, low-power asynchronous general-purpose timer;

# Introduction to the function of the work

* Two voltage inputs
* Input voltage: 1.6V - 5.5V
* Two PWM outputs
* Potentiometer dimming
* Three-way capacitive touch buttons

**This work is a case project of the LiChuang EDA training camp, used to understand the chip learning and use, the content and functions are simple and suitable for entry-level learning and use **

# Control instructions

* T0 switch (default output cold and warm 1:1)
* T1 cold light 3-speed adjustment (output out1: out2 1:0.8 1:0.6 1:0.4)
* T2 warm light 3-speed adjustment (output out1: out2 0.8:1 0.6:1 0.4:1）
* Potentiometer to adjust brightness (5 levels)

# Hardware Description

### Power input

Since this case does not need to use USB data cable for direct burning, and the microcontroller supports 3-5V wide voltage input, the light bar is also controlled by 5V, and there is no need to convert other voltage inputs, so only 6-pin USB Type-C is used as voltage input, and a CONN 2P 5mm spacing connector power input is also expanded for easy use.
![image.png]
### MUC minimum system

R7FA2E1A72DFL#AA chip only needs a simple peripheral circuit to use, without too many circuits.

**Power supply**

The R7FA2E1A72DFL microcontroller needs to ensure that all power input pins must be connected before use. Each power input pin needs to be added with a 100nF filter capacitor. The P112 pin is the reference capacitor pin of the touch button. If the touch button function is to be used, then this reference capacitor must be connected before use.

![image.png]
**Reset circuit**

The reset pin of R7FA2E1A72DFL is on the bottom 19 pin (RST). In order to reduce the size of the board, the reset circuit uses a side touch button to reduce the volume.
![image.png]
**Programming circuit**

The R7FA2E1A72DFL microcontroller programming circuit only supports serial port programming and Jlnk V7 and above versions can be programmed, and ST-lnk cannot be used.

When using the serial port programming pin, you need to pay attention to the MCU's 20th pin (MD), which is the BOOT selection of the serial port. The system defaults to pull up. When programming, you need to pull down the chip to serial port programming. You can use a pin header or button for BOOT selection.

![image.png]
### Touch capacitor button

Three-way touch capacitor button, the hardware design of the touch button needs to refer to the official standard case document for design. The touch button needs to be grounded at a single point. If it is not grounded at a single point, it may affect the sensitivity of the touch button. Please download and view the official design manual in the attachment.
![image.png]
### Potentiometer dimming input

The dimming part uses a vertical plug-in potentiometer. The microcontroller detects the ADC value and outputs PWM to change the brightness of the light strip.
![image.png]
### Two-way output

Since the light strip needs to be controlled, the current of the microcontroller io may not be able to drive, so we need a drive circuit. Here we use a very common AO3400AN channel 30V 5.8AMOS tube to form a PWM drive circuit.

![image.png]
The above is an overall circuit introduction of this training camp. I won’t explain too much about the PCB design part. You can watch the video tutorial for details.

Final note: This project is just a reference case. The works produced in the training camp need to be produced by everyone. Don’t think that Ctrl C+V is enough.