topic Re: How to program SPI on LPC54018 with another different board? in LPC Microcontrollers

SPI on LPC54018

mohd_ — Tue, 22 Dec 2020 23:42:22 GMT

Hi, does anyone know how to program SPI using LPC54018 as the master and MCP795 as the slave?

I tried with the demo codes from SDK but I dont understand well.

Thank you in advanced.

Re: How to program SPI on LPC54018 with another different board?

xiangjun_rong — Wed, 18 Nov 2020 08:38:33 GMT

Hi, Ahmad,

First of all, I think it is okay to use SPI module as master to read/write the MCP795xx.

This is connection:

LPC54018 MCP795xx:

SSELx CS

SCK SCK

MOSI SI

MISO SO

Regarding the SPI configuration:

configure the CPOL=0 and CPHA=0.

As you have seen that the SPI transfers 24 bits for each transmission. I suggest you refer to the spi_interrupt example code, but you have to rewrite the code especially the function:

void SPI_WriteData(SPI_Type *base, uint16_t data, uint32_t configFlags)
{
uint32_t control = 0U;
uint32_t instance;

/* check params */
assert(NULL != base);
/* get and check instance */
instance = SPI_GetInstance(base);

/* set data width */
control |= (uint32_t)SPI_FIFOWR_LEN((g_configs[instance].dataWidth));
/* set sssel */
control |= (SPI_DEASSERT_ALL & (~SPI_DEASSERTNUM_SSEL((uint32_t)(g_configs[instance].sselNum))));
/* mask configFlags */
control |= (configFlags & (uint32_t)SPI_FIFOWR_FLAGS_MASK);
/* control should not affect lower 16 bits */
assert(0U == (control & 0xFFFFU));
base->FIFOWR = data | control;
}

so that you can use Byte transfer, keep the /CS is low during the first 2 byte transfer, then write the third byte by setting the EOT bit in the control half word.

Hope it can help you

XiangJun rong

Re: SPI on LPC54018

mohd_ — Fri, 09 Jul 2021 06:18:08 GMT

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Re: How to program SPI on LPC54018 with another different board?

xiangjun_rong — Tue, 24 Nov 2020 06:57:06 GMT

Hi, Syamil,

This is the mechanism of the spi code, the SPI_MasterInit() initializes the SPI module, and enable interrupt, after the initialization, the SPI transmit register is empty, which trigger an SPI interrupt, the void SPI_MASTER_IRQHandler(void) is the ISR of SPI.

As you can see that the SPI_WriteData() is called in the ISR SPI_MASTER_IRQHandler(void). That is why I suggest you modify the void SPI_WriteData(SPI_Type *base, uint16_t data, uint32_t configFlags).

Hope it can help you

XiangJun Rong

void SPI_MASTER_IRQHandler(void)

{

/* read data to avoid rxOverflow */

while (SPI_GetStatusFlags(EXAMPLE_SPI_MASTER) & kSPI_RxNotEmptyFlag)

{

SPI_ReadData(EXAMPLE_SPI_MASTER);

}

/* send data if buffer is not full */

if (SPI_GetStatusFlags(EXAMPLE_SPI_MASTER) & kSPI_TxNotFullFlag)

{

if (masterIndex == 1)

{

/* need to disable interrupts before write last data */

SPI_DisableInterrupts(EXAMPLE_SPI_MASTER, kSPI_TxLvlIrq);

SPI_WriteData(EXAMPLE_SPI_MASTER, (uint16_t)(srcBuff[BUFFER_SIZE - masterIndex]), kSPI_FrameAssert);

}

else

{

SPI_WriteData(EXAMPLE_SPI_MASTER, (uint16_t)(srcBuff[BUFFER_SIZE - masterIndex]), 0);

}

masterIndex--;

}

if (masterIndex == 0U)

{

masterFinished = true;

}

/* Add for ARM errata 838869, affects Cortex-M4, Cortex-M4F Store immediate overlapping

exception return operation might vector to incorrect interrupt */

#if defined __CORTEX_M && (__CORTEX_M == 4U)

__DSB();

#endif

}

void SPI_WriteData(SPI_Type *base, uint16_t data, uint32_t configFlags)
{
uint32_t control = 0U;
uint32_t instance;

/* check params */
assert(NULL != base);
/* get and check instance */
instance = SPI_GetInstance(base);

Re: How to program SPI on LPC54018 with another different board?

mohd_ — Fri, 18 Jun 2021 00:40:10 GMT

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Re: How to program SPI on LPC54018 with another different board?

mohd_ — Wed, 02 Jun 2021 04:08:43 GMT

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