Circuit diagram and related knowledge of AT91SAM3S4C core development board

No matter what embedded software we write, we should first understand the hardware, which will help us write efficient and streamlined program code. The hardware platform we used in this event is the uTenuxAT91SAM3S4C development kit provided by Yolong Company. You can find the circuit diagram and corresponding documentation of the development board on the homepage of Yolong Company.

Open the circuit diagram. The first page is an introduction to the overall structure of the uTenuxAT91SAM3S4C development board. This development board uses ATMEIL's Cotex M3 processor ASM3S (100 pins) as the core controller. There are quite a lot of peripherals connected around the controller, which is enough for us to learn and develop. In addition, Yolong Company also provides the corresponding underlying board-level support package. In terms of programming control, we can directly refer to the application there.

The onboard peripheral units of the UTenuxAT91SAM3S4C development board include the AT91SAM3S4C reset and debugging interface unit, audio signal interface unit, USB file system unit, RS232RS485 interface unit, AD sampling unit, power management unit, TFT-LCD display unit, and SD card data storage unit, NAND-Flash unit, Q-Touch interface unit, ZigBee interface unit. The above hardware resources are relatively commonly used and are enough for us to learn and utilize.

01. AT91SAM3S4C core circuit:

The core circuit first requires us to supply power to this part, as shown in the figure below. When you see this part of the circuit, you may feel doubtful. For general processors, a total of 3.3V power supply is sufficient. Why here? Will there be a VDDOUT? How is he divine?

Please don't be surprised. When you read the power supply section of the data sheet of AT91SAM3S4C, you will understand. AT91SAM3S4C has its own power supply adjustment module. The result is as shown in the figure below. So if you have any questions, please read the data sheet in detail.

In addition to the power supply, we also need to note that the external crystal we provide for the AT91SAM3S4C is 12MHz, and there is also a 32.768kHz crystal for RTC. The others are the analog inputs of the internal ADC. 2.5V and 3.3V can be selected through jumpers. The other pin expansions will not be described in detail. We will take a closer look when they are used.

02. Reset debugging interface

The reset circuit uses a simple button to pull the reset pin low, and the debugging interface uses a standard JTAG interface, so there is nothing special about it, so this section is skipped.

03. Audio interface unit

The picture above is the audio amplification processing circuit of the uTenuxAT91SAM3S4C development board. The amplification gain can be adjusted through a jumper cap. For the specific circuit, please refer to its data sheet.

04. USB file system

Because the AT91SAM3S4C has a USB-OTG interface function internally, you only need to lead out the corresponding pin externally and refer to the data sheet.

05. RS232RS485 interface

I won’t explain the next few parts of the circuit in detail. RS232, RS485 interface and CAN bus interface are both used for industrial control. For our study, we are most exposed to RS232, so we have to pay more attention. As for the circuit details, just read the chip manual.

06. AD interface

This part of the circuit is a potentiometer voltage divider, co-processor internal ADC acquisition. No more words.

07. Power management unit

In any system, a stable power supply is the guarantee for the stable operation of the system. On the uTenuxAT91SAM3S4C development board, the designer separated the power supply for the analog part and the digital part to ensure better stability of the system. This is worth learning.

08. TFT-LCD unit

The TFT-LCD liquid crystal module is our GUI, and we must pay attention to its user-friendliness. The designers took this into consideration very well. The LCD is equipped with a backlight adjustment circuit and a touch control circuit. Please refer to the data sheet for the specific circuit principles.

09. TF card unit

The TF card unit is the core of later data storage and file system establishment, and its circuit will not be described much.

10、 Nand Flash

Please refer to the data sheet directly for the NandFlash circuit.

11. Q-Touch unit

I used STM32 to make a similar touch panel before, using two methods, namely using the STM32 internal timer to trigger detection and using the TS04 capacitance detection chip. Among them, it is relatively easy to apply the TS04 chip and its performance is stable. As for the Q-Touch on uTenuxAT91SAM3S4C, I still don’t know much about it, but after looking at Atmel’s design in this area, it is still very good and worth learning.

12. ZigBee unit

This part only leaves the ZigBee interface, not much to say.

The above is a description of the hardware circuit part. Some unclear parts still need to be studied and analyzed.