[Core board] HK32F103C8T6 minimum system

1. Project Introduction
    HK32F103C8T6 has a built-in high-performance ARM Cortex-M3 core, rich peripheral configuration, low price, ultra-low power consumption, and high cost performance. Therefore, referring to the STM32F103C8T6 minimum system, a compatible Hangshun HK32F103C8T6 minimum system is designed.
2. Onboard resources
Figure 2-1 HK32F103C8T6 core board resource diagram Main
control chip: HK32F103C8T6, LQFP-48;
Power interface: TYPE C, plug-in 2Pin;
LED display: 1 power indicator, 1 status display light;
Startup mode: BOOT mode configuration, 2x3Pin straight pin header;
Debug interface: SWD burning method, 4Pin bent pin header;
External pins: lead out programmable IO port, 2 1x20Pin straight pin headers;
3. Advantages and characteristics
Figure 3-1 HK32F103C8T6 core board size diagram
The board is small in appearance, with a size of only 53.3mm*22.9mm (2100mil*900mil);
compatible with STM32F103C8T6 and other mainstream F103 core board pinouts;
cheap, ultra-low power consumption, rich functional pins, high cost performance;
using Jiali Chuang high-quality PCB and genuine components to ensure product quality;
IV. Circuit analysis
Figure 4-1 SCH_HK32F103C8T6 minimum system
1. Power supply circuit
  The power supply circuit is mainly composed of TYPE-C power supply circuit and LDO-5V to 3.3V circuit, using 2Pin TYPE-C interface, simple and convenient, easy to weld.
 Figure 4-2 TYPE-C power supply circuit
      LDO-5V to 3.3V step-down circuit, the 5V input of the TYPE-C power supply circuit is stepped down by LDO to output 3.3V, which supplies power to the main control chip. The capacitor acts as a filter to make the output voltage signal more stable.
Figure 4-3 LDO-5V to 3.3V circuit
2. The main control circuit
      HK32F103C8T6 pins can be roughly divided into four categories: power, clock, control and I/O pins; Figure 4-4 is the pin definition diagram of HK32F103C8T6, and the definition and reuse of each pin are explained below.
VBAT (1.8-5.5V): connect to external battery, power supply for RTC, external oscillator and backup register, can be connected to power supply if not needed;
VDD (2.0-5.5V): power supply voltage of MCU, power supply for I/O pins and internal LDO;
VDDA (2.0-5.5V): power supply for analog devices such as ADC and temperature sensor inside the chip;
VSS: ground terminal of MCU;
VSSA: common ground of analog devices;
OSC32_IN: inverting input terminal of crystal oscillator circuit;
OSC32_OUT: inverting output terminal of crystal oscillator circuit;
PC13-TAMPER-RTC: external interface of IO port/RTC, with intrusion detection function. When the pin level status changes, an intrusion detection event will be generated, and the intrusion detection event will clear the contents of all data backup registers.
PC14-OSC32_IN/PC15-OSC32_OUT: external low-speed crystal oscillator (RTC crystal oscillator IO);
PD0-OSC32_IN/PD1-OSC_OUT: external high-speed crystal oscillator (main crystal oscillator IO);
NRST: reset pin, used for external manual reset;
BOOT0/BOOT1: boot setting pin, which determines the boot mode of the system by reading the interface status during startup;
Figure 4-4 HK32F103C8T6 (LQFP48) pin definition diagram
 
  All HK32F103C8T6 pins are brought out to facilitate expansion project development. The capacitor here is for filtering. When drawing the PCB, it should be placed as close to the chip pins as possible. The main control circuit pin connection method is shown in Figure 4-5.
Figure 4-5 HK32F103C8T6 main control circuit
3. Crystal oscillator circuit
  The function of the crystal oscillator is to provide a clock signal for the minimum system. The function of the capacitor next to the crystal oscillator is to ensure that the output oscillation frequency is more stable. The 32.768kHz crystal oscillator provides a clock signal for the RTC, and the 8MHz crystal oscillator circuit provides a clock signal for the microcontroller. If the RTC function is not used, the RTC crystal oscillator can be disconnected.
 
Figure 4-6 RTC crystal oscillator
circuit Figure 4-7 Main crystal oscillator circuit
4. Reset circuit
  Reset is also called restart. Press the SW1 button, the main control NRST pin is pulled low, and an external reset pulse is generated to reset the system; release the SW1 button to restore the normal working state, and the reset pin is in a high level state.
Figure 4-8 Reset circuit
5.
  When the peripheral circuit is powered on, the power indicator (red) lights up, proving that the power supply part of the minimum system is working normally. The test status display light (blue) is used to test the PC13 pin of the microcontroller, and the test light is turned on and off through the program.
Figure 4-9 The LED indicator circuit
  adopts SWD burning mode, and a 1x4Pin bent pin header interface is reserved for downloading and debugging simulation programs. The capacitor acts as a filter to make the download and burning performance more stable.
Figure 4-10 Download circuit
  Before downloading and burning, the high and low levels of the two pins BOOT0 and BOOT1 must be used to control the boot mode of the microcontroller to successfully download the program. The detailed configuration is shown in Table 1-1 below.
Figure 4-11 BOOT mode selection
Table 1-1 BOOT pin configuration Boot mode


Boot mode selection pin


Boot mode


description


BOOT0


BOOT1


0


X


User flash


memory Flash built-in in the chip


1


0


System memory/ISP


chip internal specific Bootloader area


1


1


Internal SRAM


chip built-in RAM area (memory)


 
When using SWD burning, BOOT0 and BOOT1 need to be grounded.
When using serial port ISP burning, BOOT0 needs to be connected to the power supply and BOOT1 needs to be grounded.
  It is convenient to expand the project and verify various functions. Two 1x20Pin 2.54mm pin headers are used to bring out the I/O pins of the microcontroller, which is compatible with the pin arrangements of other mainstream microcontroller core boards.
Figure 4-12 External IO port
V. Bill of Materials


BOM_HK32F103C8T6 Minimum System


No.


Name


Parameter Device


Position No.


Quantity


Package


Item No.


1


Resistor


1kΩ


R1,R2


2


R0603


C21190


10kΩ


R3


1


C25804


2


Capacitor


12pF


C10~C13


4


C0603


C1642


100nF


C2,C4,C5~C9,C14


8


C30926


1uF


C1,C3


2


C59302


3


LED


Red light


LED1


1


LED0603


C84263


Blue light


LED2


1


C72041


4


Button


TS-1101-BW


SW1


1


KEY-SMD_2P


C500065


5


Crystal oscillator


32.768kHz


X1


1


MC-306


C16320


8MHz


X2


1


HC-49S-2P


C21263


6


MCU


HK32F103C8T6


U1


1


LQFP-48


C482563


7


LDO


ME6211C33M5G


U2


1


SOT-23-5


C82942


8


-pin


2.54mm 1x4P elbow plug


H1


1


HDR-TH_4P-P2.54


C2935929


2.54mm 2x3P straight plug


H2


1


HDR-TH_6P-P2.54


C492420


2.54mm 1x20P straight plug


H3,H4


2


HDR-TH_20P-P2.54


C429964


9


USB


TYPE-C-2Pin


USB1


1


TYPE-C-TH-2Pin


C2848624


VI. Precautions
When drawing the schematic diagram, you should pay attention to the following:
Draw according to the module circuit division and indicate the circuit function;
unused pins should be placed with non-connection symbols, which is professional and standardized;
fill in the project name and other information on the drawing properties;
 
When purchasing materials, you should pay attention to the following:
first filter the materials in stock, then filter the price and sort them;
try to purchase materials from the same warehouse, choose a warehouse close to each other, and shorten the delivery time;
when purchasing multiple orders, you can save shipping costs by binding orders;
 
In PCB Layout, you should pay attention to the following:
the main control chip is placed at 45 degrees, which is convenient for routing the external pin headers with the expansion pins;
the filter capacitor should pay attention to the current flow direction and try to be closer to the components to be filtered;
the crystal oscillator should be as close to the chip as possible, and no routing should be done at the bottom to prevent signal crosstalk;
routing should preferably be straight, and obtuse angles or arcs should be used where turns are required;
after drawing and adjusting the PCB, add teardrops to make the board more beautiful and stable;
add silk screen logos and annotate the interface functions;
JLCJLCJLCJLC specifies that the custom silk screen can be hidden under the device, and the finished board is beautiful;
Figure 6-1-1 PCB routing reference diagram - top layer
diagram 6-1-2 PCB routing reference diagram - bottom layer
 
Notes during welding:
When welding, you can click the welding auxiliary tool in the toolbar of Jiali Chuang EDA, and interact in real time to facilitate welding;
when welding the top layer, it is recommended to give priority to welding the main control chip to avoid other devices affecting welding; when
welding the pin header, you can use an empty board or a perforated board to support it to prevent welding from being slanted and affecting use;
the welding sequence should follow the principle of from low to high to avoid affecting the welding of small devices;
Figure 6-2-1 PCB empty board - top layer
Figure 6-2-2 PCB empty board - bottom layer
Figure 6-3-1 PCBA physical picture - top surface
Figure 6-3-2 PCBA physical picture - bottom surface
Figure 6-4 The following points
should be noted when debugging the 3D renderings :
Before power-on debugging, check whether there are problems such as cold soldering and short circuits. Only after the inspection is correct can the power-on test be carried out;
when using SWD burning, BOOT0 and BOOT1 need to be grounded with short-circuit caps;
the HK32F103 support package (https://www.hsxp-hk.com/companyfile/167/) needs to be downloaded and installed in advance;
Figure 6-5 HK32F103C8T6 minimum system working diagram