{"id":5334,"date":"2021-03-04T03:56:24","date_gmt":"2021-03-04T03:56:24","guid":{"rendered":"http:\/\/fastbitlab.com\/?p=5334"},"modified":"2023-09-04T15:39:56","modified_gmt":"2023-09-04T10:09:56","slug":"usart-driver-api-send-data","status":"publish","type":"post","link":"https:\/\/fastbitlab.com\/blog\/usart-driver-api-send-data\/","title":{"rendered":"STM32 USART Lecture 6 – USART Driver API: Send data"},"content":{"rendered":"
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USART Driver API: Send data<\/span><\/strong><\/h1>\n
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In this article, let\u2019s understand USART_SendDataAPI used to send data from the USART peripheral to the external world.<\/span><\/p>\n

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Steps of implementation:<\/b><\/span><\/p>\n

1. First of all, there is a for loop that is to loop over until the \u201cLen\u201d number of bytes are transferred.<\/span><\/p>\n

\"USART
Figure 1. for loop to transfer \u201cLen\u201d number of bytes.<\/span><\/figcaption><\/figure>\n

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2. Since it is a serial communication peripheral just like I2C or SPI, it also has TXE in the SR register and you have to wait until the TXE is set (Figure 2), which is an indication to make sure that the transmit data register (TDR) in the peripheral is empty.<\/span><\/p>\n

\"USART
Figure 2. Code to check the TXE flag.<\/span><\/figcaption><\/figure>\n

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3. After that, you have to make the decision whether you are transmitting 9 bits in a frame or 8 bits in a frame. Because if you take a look into the word length programming diagram of the reference manual (Figure 3), there are two options for control bit M.<\/span><\/p>\n