topic Re: PRESETCTRL in LPC Microcontrollers

PRESETCTRL

berndsirozynski — Fri, 25 Aug 2017 11:12:58 GMT

Hello,

i am using the LPC1347.

There is a register named PRESETCTRL.

With this register i can reset the Hardware from SSP0, I2C and SSP1.

To Reset the Hardware i must clear then coresponding bit to "0"

To activate the peripheral i must set the bit to "1"

Question: Is there a minimum time limit, between reset and set to this bit,

so the Hardware can do the internal reset operation ?

Reset the Bit

delay(xxx)

Set the Bit

wait until ready ???

after doing the reset, do i need to wait until Hardware is ready ???

very thanks for information

Bernd

Re: PRESETCTRL

kerryzhou — Mon, 28 Aug 2017 03:30:33 GMT

Hi Bernd Sirozynski,

The datasheet didn't give out the minimum, so I think you don't need to care about this time.

You also don't need to add the delay to wait the hardware reset is ready.

I have checked the official lpcopen code, take spi as an example, the peripheral reset code is wrote like this:

STATIC INLINE void Chip_SYSCTL_PeriphReset(CHIP_SYSCTL_PERIPH_RESET_T periph)
{
Chip_SYSCTL_AssertPeriphReset(periph);
Chip_SYSCTL_DeassertPeriphReset(periph);
}

void Chip_SSP_Init(LPC_SSP_T *pSSP)
{
    Chip_Clock_EnablePeriphClock(Chip_SSP_GetClockIndex(pSSP));
    Chip_SSP_SetSSPClkDivider(pSSP, 1);
    Chip_SYSCTL_PeriphReset(Chip_SSP_GetResetIndex(pSSP));

   Chip_SSP_Set_Mode(pSSP, SSP_MODE_MASTER);
   Chip_SSP_SetFormat(pSSP, SSP_BITS_8, SSP_FRAMEFORMAT_SPI, SSP_CLOCK_CPHA0_CPOL0);
   Chip_SSP_SetBitRate(pSSP, 100000);
}

STATIC INLINE void Chip_SYSCTL_AssertPeriphReset(CHIP_SYSCTL_PERIPH_RESET_T periph)
{
LPC_SYSCTL->PRESETCTRL &= ~(1 << (uint32_t) periph);
}

STATIC INLINE void Chip_SYSCTL_DeassertPeriphReset(CHIP_SYSCTL_PERIPH_RESET_T periph)
{
LPC_SYSCTL->PRESETCTRL |= (1 << (uint32_t) periph);
}

You can find no delay and wait, so just write the code like the official code.

Wish it helps you!

Have a great day,
Kerry

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Re: PRESETCTRL

berndsirozynski — Tue, 19 Dec 2017 09:58:49 GMT

Oh whats that ?
have i forgot to thank you kerry ????
Sorry, that is not my style.
Have very thanks for your good information.
and i wish a you a nice Christmas.

Bernd

Re: PRESETCTRL

kerryzhou — Wed, 20 Dec 2017 01:06:17 GMT

Hi Bernd,

It doesn't matter, thanks for your updated information.

Merry Christmas to you! :smileyhappy:

Have a great day,
Kerry