STM32 Blue Pill HSPI1 and SN74HC595N LED Example

The SN74HC595N is an 8-bit serial-in-parallel out shift registers with latch outputs. It also has a serial data (DS) out pin for additional register cascading. This chip could operate at +3.3V level that could fit the STM32 micro-controller. For more information about using this chip, see this post.

SN74HC595N LED Shift

 

This chip use a three-wire SPI interface, MOSI, SCK and Enable Pin for SPI master mode half duplex micro-controller. I made my own test board for this chip that outputs to LEDs.

DIY SN74HC595N LED Test Board

 

The STM32CubeIDE has its code configure wizard enables the user to select any hardware and software setting of its micro-controller. Using HAL is very straight forward for writing code without using the micro-controller internal special registers.

The STM32F103C8T6 has two hardware SPI module, HSPI1 and HSPI2 that able to operate up to 16Mbits/s. 

I set the micro-controller to operate at 64MHz using its HSI and PLL. The SPI mode is Half Duplex Master with a 16MBits/s Baud Rate.

Clock Configuration

 

The SPI NSS pin is can not be use with the SN74HC595. So the Enable pin must be select by user's software. I use the PA4 pin for the SPI enable pin.

SPI and GPIO Setting

After the setting is finished click on generate code to get its skeleton program. The example below is a LED bar-graph that repeated endlessly. 

1. /* USER CODE BEGIN Header */
2. /**
3. ******************************************************************************
4. * @file : main.c
5. * @brief : Main program body
6. ******************************************************************************
7. * @attention
8. *
9. * <h2><center>&copy; Copyright (c) 2025 STMicroelectronics.
10. * All rights reserved.</center></h2>
11. *
12. * This software component is licensed by ST under BSD 3-Clause license,
13. * the "License"; You may not use this file except in compliance with the
14. * License. You may obtain a copy of the License at:
15. * opensource.org/licenses/BSD-3-Clause
16. *
17. ******************************************************************************
18. */
19. /* USER CODE END Header */
20. /* Includes ------------------------------------------------------------------*/
21. #include "main.h"
22. 
    
23. /* Private includes ----------------------------------------------------------*/
24. /* USER CODE BEGIN Includes */
25. 
    
26. /* USER CODE END Includes */
27. 
    
28. /* Private typedef -----------------------------------------------------------*/
29. /* USER CODE BEGIN PTD */
30. 
    
31. /* USER CODE END PTD */
32. 
    
33. /* Private define ------------------------------------------------------------*/
34. /* USER CODE BEGIN PD */
35. /* USER CODE END PD */
36. 
    
37. /* Private macro -------------------------------------------------------------*/
38. /* USER CODE BEGIN PM */
39. 
    
40. /* USER CODE END PM */
41. 
    
42. /* Private variables ---------------------------------------------------------*/
43. SPI_HandleTypeDef hspi1;
44. 
    
45. /* USER CODE BEGIN PV */
46. 
    
47. /* USER CODE END PV */
48. 
    
49. /* Private function prototypes -----------------------------------------------*/
50. void SystemClock_Config(void);
51. static void MX_GPIO_Init(void);
52. static void MX_SPI1_Init(void);
53. /* USER CODE BEGIN PFP */
54. 
    
55. /* USER CODE END PFP */
56. 
    
57. /* Private user code ---------------------------------------------------------*/
58. /* USER CODE BEGIN 0 */
59. 
    
60. /* USER CODE END 0 */
61. 
    
62. /**
63. * @brief The application entry point.
64. * @retval int
65. */
66. int main(void)
67. {
68. /* USER CODE BEGIN 1 */
69. 
    
70. /* USER CODE END 1 */
71. 
    
72. /* MCU Configuration--------------------------------------------------------*/
73. 
    
74. /* Reset of all peripherals, Initializes the Flash interface and the Systick. */
75. HAL_Init();
76. 
    
77. /* USER CODE BEGIN Init */
78. 
    
79. /* USER CODE END Init */
80. 
    
81. /* Configure the system clock */
82. SystemClock_Config();
83. 
    
84. /* USER CODE BEGIN SysInit */
85. 
    
86. /* USER CODE END SysInit */
87. 
    
88. /* Initialize all configured peripherals */
89. MX_GPIO_Init();
90. MX_SPI1_Init();
91. /* USER CODE BEGIN 2 */
92. 
    
93. /* USER CODE END 2 */
94. uint8_t data=0, i=0;
95. /* Infinite loop */
96. /* USER CODE BEGIN WHILE */
97. while (1)
98. {
99. data|=(1<<i);
100. if(data==0xFF) data=0;
101. i++;
102. if(i>7) i=0;
103. HAL_SPI_Transmit(&hspi1,&data,1,10);
104. 
     
105. HAL_GPIO_WritePin(GPIOA,GPIO_PIN_4,0);
106. HAL_Delay(100);
107. HAL_GPIO_WritePin(GPIOA,GPIO_PIN_4,1);
108. }
109. /* USER CODE END 3 */
110. }
111. 
     
112. /**
113. * @brief System Clock Configuration
114. * @retval None
115. */
116. void SystemClock_Config(void)
117. {
118. RCC_OscInitTypeDef RCC_OscInitStruct = {0};
119. RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
120. 
     
121. /** Initializes the RCC Oscillators according to the specified parameters
122. * in the RCC_OscInitTypeDef structure.
123. */
124. RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI;
125. RCC_OscInitStruct.HSIState = RCC_HSI_ON;
126. RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
127. RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
128. RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSI_DIV2;
129. RCC_OscInitStruct.PLL.PLLMUL = RCC_PLL_MUL16;
130. if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
131. {
132. Error_Handler();
133. }
134. /** Initializes the CPU, AHB and APB buses clocks
135. */
136. RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
137. |RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;
138. RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
139. RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
140. RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV2;
141. RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;
142. 
     
143. if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_2) != HAL_OK)
144. {
145. Error_Handler();
146. }
147. }
148. 
     
149. /**
150. * @brief SPI1 Initialization Function
151. * @param None
152. * @retval None
153. */
154. static void MX_SPI1_Init(void)
155. {
156. 
     
157. /* USER CODE BEGIN SPI1_Init 0 */
158. 
     
159. /* USER CODE END SPI1_Init 0 */
160. 
     
161. /* USER CODE BEGIN SPI1_Init 1 */
162. 
     
163. /* USER CODE END SPI1_Init 1 */
164. /* SPI1 parameter configuration*/
165. hspi1.Instance = SPI1;
166. hspi1.Init.Mode = SPI_MODE_MASTER;
167. hspi1.Init.Direction = SPI_DIRECTION_1LINE;
168. hspi1.Init.DataSize = SPI_DATASIZE_8BIT;
169. hspi1.Init.CLKPolarity = SPI_POLARITY_LOW;
170. hspi1.Init.CLKPhase = SPI_PHASE_1EDGE;
171. hspi1.Init.NSS = SPI_NSS_SOFT;
172. hspi1.Init.BaudRatePrescaler = SPI_BAUDRATEPRESCALER_4;
173. hspi1.Init.FirstBit = SPI_FIRSTBIT_MSB;
174. hspi1.Init.TIMode = SPI_TIMODE_DISABLE;
175. hspi1.Init.CRCCalculation = SPI_CRCCALCULATION_DISABLE;
176. hspi1.Init.CRCPolynomial = 10;
177. if (HAL_SPI_Init(&hspi1) != HAL_OK)
178. {
179. Error_Handler();
180. }
181. /* USER CODE BEGIN SPI1_Init 2 */
182. 
     
183. /* USER CODE END SPI1_Init 2 */
184. 
     
185. }
186. 
     
187. /**
188. * @brief GPIO Initialization Function
189. * @param None
190. * @retval None
191. */
192. static void MX_GPIO_Init(void)
193. {
194. GPIO_InitTypeDef GPIO_InitStruct = {0};
195. 
     
196. /* GPIO Ports Clock Enable */
197. __HAL_RCC_GPIOA_CLK_ENABLE();
198. 
     
199. /*Configure GPIO pin Output Level */
200. HAL_GPIO_WritePin(GPIOA, GPIO_PIN_4, GPIO_PIN_RESET);
201. 
     
202. /*Configure GPIO pin : PA4 */
203. GPIO_InitStruct.Pin = GPIO_PIN_4;
204. GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
205. GPIO_InitStruct.Pull = GPIO_NOPULL;
206. GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
207. HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
208. 
     
209. }
210. 
     
211. /* USER CODE BEGIN 4 */
212. 
     
213. /* USER CODE END 4 */
214. 
     
215. /**
216. * @brief This function is executed in case of error occurrence.
217. * @retval None
218. */
219. void Error_Handler(void)
220. {
221. /* USER CODE BEGIN Error_Handler_Debug */
222. /* User can add his own implementation to report the HAL error return state */
223. __disable_irq();
224. while (1)
225. {
226. }
227. /* USER CODE END Error_Handler_Debug */
228. }
229. 
     
230. #ifdef USE_FULL_ASSERT
231. /**
232. * @brief Reports the name of the source file and the source line number
233. * where the assert_param error has occurred.
234. * @param file: pointer to the source file name
235. * @param line: assert_param error line source number
236. * @retval None
237. */
238. void assert_failed(uint8_t *file, uint32_t line)
239. {
240. /* USER CODE BEGIN 6 */
241. /* User can add his own implementation to report the file name and line number,
242. ex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */
243. /* USER CODE END 6 */
244. }
245. #endif /* USE_FULL_ASSERT */
246. 
     
247. /************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/

Proteus VSM also has a model for the STM32 Blue Pill for simulation.

 

I tested on bread board with my SN74HC595N LED module. It works fine. We can connect the supply voltage pin of the SN74HC595N to +5VDC while the STM32 Blue pill operates at only +3.3VDC. Or even both of them connect to the +3.3VDC they still works.

SN74HC595N LED Bar-Graph

Now I made a little source code modification to make a simple LED shifting. 

1. while (1)
2. {
3. data=(1<<i);
4. //if(data==0xFF) data=0;
5. i++;
6. if(i>7) i=0;
7. HAL_SPI_Transmit(&hspi1,&data,1,10);
8. 
   
9. HAL_GPIO_WritePin(GPIOA,GPIO_PIN_4,0);
10. HAL_Delay(100);
11. HAL_GPIO_WritePin(GPIOA,GPIO_PIN_4,1);
12. }

SN74HC595N LED Shift

SN74HC595N LED Shift

 

Click here to download its source file.