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Document USART driver

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This commit is contained in:
Steins7 2024-04-06 22:19:19 +02:00
parent 85e7ad5ef1
commit c6da4e11d8
2 changed files with 86 additions and 30 deletions
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57
drv/usart.c
View File

@ -8,7 +8,6 @@
//--includes--------------------------------------------------------------------
#include "usart.h"
#include "nvic.h"
#include "usart_regs.h"
#include "reg.h"
@ -106,6 +105,33 @@ void usart_configure(enum UsartPeriph periph, enum UsartConfig config,
}
}
uint32_t usart_read_byte(enum UsartPeriph periph, uint8_t* byte)
{
volatile struct USART* regs;
switch (periph) {
case USART_PERIPH_1:
regs = usart1;
break;
case USART_PERIPH_2:
regs = usart2;
break;
case USART_PERIPH_3:
regs = usart3;
break;
default:
return 1;
break;
}
if (regs->SR.RXNE) {
*byte = regs->DR.DR;
return 0;
} else {
return 1;
}
}
uint32_t usart_write_byte(enum UsartPeriph periph, uint8_t byte)
{
volatile struct USART* regs;
@ -134,33 +160,6 @@ uint32_t usart_write_byte(enum UsartPeriph periph, uint8_t byte)
}
}
uint32_t usart_read_byte(enum UsartPeriph periph, uint8_t* byte)
{
volatile struct USART* regs;
switch (periph) {
case USART_PERIPH_1:
regs = usart1;
break;
case USART_PERIPH_2:
regs = usart2;
break;
case USART_PERIPH_3:
regs = usart3;
break;
default:
return 1;
break;
}
if (regs->SR.RXNE) {
*byte = regs->DR.DR;
return 0;
} else {
return 1;
}
}
const struct DmaParam* usart_configure_rx_dma(enum UsartPeriph periph)
{
const struct DmaParam* param;
@ -295,7 +294,7 @@ static void configure_usart(volatile struct USART* regs,
/**
* Configure the given registers with the given baudrate. Baudrate is dependant
* on the peripheric's clock and may not be exact due to precision errors (see
* on the peripheral's clock and may not be exact due to precision errors (see
* table 192 in documentation)
*/
static void configure_baudrate(volatile struct USART* regs, uint32_t clock,

59
drv/usart.h
View File

@ -17,12 +17,19 @@
//--type definitions------------------------------------------------------------
/**
* Available USART peripherals. Note that some of these peripherals may not be
* available on all chips
*/
enum UsartPeriph {
USART_PERIPH_1,
USART_PERIPH_2,
USART_PERIPH_3,
};
/**
* Available configuration options
*/
enum UsartConfig {
USART_CONFIG_7E1,
USART_CONFIG_7E2,
@ -39,14 +46,64 @@ enum UsartConfig {
//--functions-------------------------------------------------------------------
/**
* Configures the given USART peripheral using the provided condiguration
* options and baudrate. The baudrate may be any value supported by the
* peripheral, though some may not be exact due to precision errors (see
* table 192 in documentation). The baudrate is dependant on the peripheral's
* clock and changes to the later after this function has been called will cause
* the effective baudrate to change
*
* This function doesn't configure the required ports. This should be done using
* the gpio driver:
* - Tx port should be using GPIO_CONFIG_OUT_ALT_PUSH_PULL with
* the appropriate output speed based on the baurate (see GpioMode)
* - Rx port should be using GPIO_CONFIG_IN_FLOATING in input mode
* Both ports do not need to be configured if not used (e.g. if only using Tx,
* the Rx port can be left unconfigured)
*/
void usart_configure(enum UsartPeriph periph, enum UsartConfig config,
uint32_t baudrate);
/**
* Resets the given USART peripheral, applying the default configuration and
* disabling it
*/
void usart_reset(enum UsartPeriph periph);
uint32_t usart_write_byte(enum UsartPeriph periph, uint8_t byte);
/**
* Reads a single byte to the given USART peripheral, returning 0 if
* successfull, 1 otherwise.
*
* The Rx port must be configured for this function to ever return successfully
*/
uint32_t usart_read_byte(enum UsartPeriph periph, uint8_t* byte);
/**
* Writes a single byte to the given USART peripheral, returning 0 if
* successfull, 1 otherwise.
*
* The Tx port must be configured for this function to do anything, though the
* function would still return 0
*/
uint32_t usart_write_byte(enum UsartPeriph periph, uint8_t byte);
/**
* Configures the given USART peripheral for DMA Rx operations, returning the
* corresponding DMA parameters to be used.
*
* The DMA must be configured separately using the DMA driver or an existing
* service
*/
const struct DmaParam* usart_configure_rx_dma(enum UsartPeriph periph);
/**
* Configures the given USART peripheral for DMA Rx operations, returning the
* corresponding DMA parameters to be used.
*
* The DMA must be configured separately using the DMA driver or an existing
* service
*/
const struct DmaParam* usart_configure_tx_dma(enum UsartPeriph periph);