Detailed Description

UART driver implementation for a EUSCIA peripheral for MSP432.

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Stack requirements

The UARTMSP432 driver is (ring) buffered driver where it stores data it may already received in a user-supplied background buffer.

See also: UARTMSP432_HWAttrs

While permitted, it is STRONGLY suggested to avoid implementations where you call UART_read() within it own callback function (when in UART_MODE_CALLBACK).

Doing so, will require additional (task and system) stack for each nested UART_read() call.

Tool chain	Number of bytes per nested UART_read() call
GNU	96 bytes + callback function stack requirements
IAR	40 bytes + callback function stack requirements
TI	80 bytes + callback function stack requirements

It is important to note a potential worst case scenario: A full ring buffer with data; say 32 bytes The callback function calls UART_read() with a size of 1 (byte) No other variables are allocated in the callback function No other function calls are made in the callback function

As a result, you need an additional task and system stack of: 32 bytes * (80 bytes for TI + 0 bytes by the callback function) = 2.5kB

The UART header file should be included in an application as follows:

#include <ti/drivers/UART.h>

#include <ti/drivers/uart/UARTMSP432.h>

This UART driver implementation is designed to operate on a EUSCI controller in UART mode for MSP432 devices.

#include <stdint.h>
#include <stdbool.h>
#include <ti/drivers/ports/ClockP.h>
#include <ti/drivers/ports/HwiP.h>
#include <ti/drivers/ports/SemaphoreP.h>
#include <ti/drivers/Power.h>
#include <ti/drivers/UART.h>
#include <ti/drivers/uart/RingBuf.h>

Include dependency graph for UARTMSP432.h:

Go to the source code of this file.

Data Structures
struct	UARTMSP432_FxnSet
	Complement set of read functions to be used by the UART ISR and UARTMSP432_read(). Internal use only. More...

struct	UARTMSP432_BaudrateConfig
	UARTMSP432 Baudrate configuration. More...

struct	UARTMSP432_HWAttrs
	UARTMSP432 Hardware attributes. More...

struct	UARTMSP432_Object
	UARTMSP432 Object. More...

Typedefs
typedef struct UARTMSP432_FxnSet	UARTMSP432_FxnSet
	Complement set of read functions to be used by the UART ISR and UARTMSP432_read(). Internal use only. More...

typedef struct UARTMSP432_BaudrateConfig	UARTMSP432_BaudrateConfig
	UARTMSP432 Baudrate configuration. More...

typedef struct UARTMSP432_HWAttrs	UARTMSP432_HWAttrs
	UARTMSP432 Hardware attributes. More...

typedef struct UARTMSP432_Object	UARTMSP432_Object
	UARTMSP432 Object. More...

typedef struct UARTMSP432_Object *	UARTMSP432_Handle

Variables
const UART_FxnTable	UARTMSP432_fxnTable

Typedef Documentation

typedef struct UARTMSP432_FxnSet UARTMSP432_FxnSet

Complement set of read functions to be used by the UART ISR and UARTMSP432_read(). Internal use only.

These functions should not be used by the user and are solely intended for the UARTMSP432 driver. The UARTMSP432_FxnSet is a pair of complement functions that are design to operate with one another in a task context and in an ISR context. The readTaskFxn is called by UARTMSP432_read() to drain a circular buffer, whereas the readIsrFxn is used by the UARTMSP432_hwiIntFxn to fill up the circular buffer.

readTaskFxn: Function called by UART read These variables are set and available for use to the readTaskFxn. object->readBuf = buffer; //Pointer to a user buffer object->readSize = size; //Desired no. of bytes to read object->readCount = size; //Remaining no. of bytes to read

readIsrFxn: The required ISR counterpart to readTaskFxn

typedef struct UARTMSP432_BaudrateConfig UARTMSP432_BaudrateConfig

UARTMSP432 Baudrate configuration.

This structure is used to specifiy the EUSCI controller's clock divider settings to achieve the desired baudrate given the a clock input frequency. Divider values can be determined by referring to the MSP430 baudrate calculator. http://software-dl.ti.com/msp430/msp430_public_sw/mcu/msp430/MSP430BaudRateConverter/index.html

A sample structure is shown below:

 const UARTMSP432_BaudrateConfig uartBaudrates[] = {
     // {baudrate, input clock, prescalar, UCBRFx, UCBRSx, oversampling}
     {
         .outputBaudrate = 115200,
         .inputClockFreq = 12000000,
         .prescalar = 6,
         .hwRegUCBRFx = 8,
         .hwRegUCBRSx = 32,
         .oversampling = 1
     },
     {115200, 6000000,   3,  4,   2, 1},
     {115200, 3000000,   1, 10,   0, 1},
     {9600,   12000000, 78,  2,   0, 1},
     {9600,   6000000,  39,  1,   0, 1},
     {9600,   3000000,  19,  8,  85, 1},
     {9600,   32768,     3,  0, 146, 0}
 };

typedef struct UARTMSP432_HWAttrs UARTMSP432_HWAttrs

UARTMSP432 Hardware attributes.

These fields are used by driverlib APIs and therefore must be populated by driverlib macro definitions. For MSP432Ware these definitions are found in:

uart.h

A sample structure is shown below:

 unsigned char uartMSP432RingBuffer[2][32];
 
 const UARTMSP432_HWAttrs uartMSP432HWAttrs[MSP_EXP432P401RLP_UARTCOUNT] = {
     {
         .baseAddr = EUSCI_A0_BASE,
         .intNum = INT_EUSCIA0,
         .intPriority = (~0),
         .clockSource = EUSCI_A_UART_CLOCKSOURCE_SMCLK,
         .bitOrder = EUSCI_A_UART_LSB_FIRST,
         .numBaudrateEntries = sizeof(uartMSP432Baudrates) /
                               sizeof(UARTMSP432_BaudrateConfig),
         .baudrateLUT = uartMSP432Baudrates,
         .ringBufPtr  = uartMSP432RingBuffer[0],
         .ringBufSize = sizeof(uartMSP432RingBuffer[0])
     },
     {
         .baseAddr = EUSCI_A2_BASE,
         .intNum = INT_EUSCIA2,
         .intPriority = (~0),
         .clockSource = EUSCI_A_UART_CLOCKSOURCE_SMCLK,
         .bitOrder = EUSCI_A_UART_LSB_FIRST,
         .numBaudrateEntries = sizeof(uartMSP432Baudrates) /
                               sizeof(UARTMSP432_BaudrateConfig),
         .baudrateLUT = uartMSP432Baudrates
         .ringBufPtr  = uartMSP432RingBuffer[1],
         .ringBufSize = sizeof(uartMSP432RingBuffer[1])
     }
 };

typedef struct UARTMSP432_Object UARTMSP432_Object

UARTMSP432 Object.

The application must not access any member variables of this structure!

typedef struct UARTMSP432_Object * UARTMSP432_Handle

Variable Documentation

const UART_FxnTable UARTMSP432_fxnTable

Detailed Description

Stack requirements

Data Structures

Typedefs

Variables

Typedef Documentation

Variable Documentation