I am trying to find in the User manual what the clock speed I am running at. I
have a Super Pro Plus. According to the PCLK_SPI bits in the PCLKSEL0 register
they are set by default to 00 (CCLK/4). But what is this speed? I think the
CCLK is dependent on the PLL clock but I do not know where to find the info I am
looking for.
Basically I have to keep my SPI under 10 MHz for one of my SPI slave devices. I
do not know what to set the PCLK_SPI bits to if I do not know what the CCLK is.
The external crystal is 32kHz, correct?
SPI clock speed
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- Posts: 1462
- Joined: Fri Oct 19, 2012 5:11 am
Re: SPI clock speed
CCLK is 96 MHz
PCLK is 24 MHz
PCLK is 24 MHz
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- Posts: 1462
- Joined: Fri Oct 19, 2012 5:11 am
Re: SPI clock speed
Ok, thanks. But the only choices for PCLKSEL0 are CCLK, CCLK/2, CCLK/4, and
CCLK/8. CCLK/8 will only give me 96/8= 12MHz. My max for my slave device is
10MHz. How and what do I change to get this down to 10 MHz?
CCLK/8. CCLK/8 will only give me 96/8= 12MHz. My max for my slave device is
10MHz. How and what do I change to get this down to 10 MHz?
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- Posts: 1462
- Joined: Fri Oct 19, 2012 5:11 am
Re: SPI clock speed
If you change PCLK you change it for all peripherals in the LPC17xx family, a
bad thing in BASIC
But almost all peripherals have pre-scalers of some sort to control the
frequency
in the SPI it's the S0SPCCR
in the 2 SSPs it's the CPSR
bad thing in BASIC
But almost all peripherals have pre-scalers of some sort to control the
frequency
in the SPI it's the S0SPCCR
in the 2 SSPs it's the CPSR