mios32_spi.c

MIOS programming (C)
1

Hi,

I was trying to understand the configuration in mios32_spi.c and I am wondering if I don’t understand it right or there is a small mistake…

From line 76 to 79 there is the initalization of the IO-Pins:

// Push-Pull Config

#define MIOS32_SPI0_PP_INIT { LPC_PINCON->PINMODE_OD1 &= ~((1 << 24) | (1 << 23) | (1 << 22) | (1 << 21) | (1 << 20)); }

// Open-Drain Config – NOTE: unfortunately it has no effect on SCLK and MOSI pin! This isn’t documented in the LPC17xx user manual

#define MIOS32_SPI0_OD_INIT { LPC_PINCON->PINMODE_OD1 |= ((1 << 24) | (1 << 23) | (1 << 22) | (1 << 21) | (1 << 20)); }

The macro MIOS32_SPI0_PP_INIT calls PINMODE_OD1 to set the resistor configuration but instead it clears the open drain mode and the next macro sets them again.

Or why is the headline Push-Pull Config?

Can somebody help?

Best,

braintu

EDIT:

Sorry for bothering. I understood the push/pull comment wrong. It refers to the output which push/pull-s not to the resistors…

2

PINMODE_OD1 isn’t a function, but a configuration register of the LPC17 port peripheral.

MIOS32_SPI0_PP_INIT applies an AND mask over this register, which means that bits will be cleared (-> OD function for given pins disabled)

MIOS32_SPI0_OD_INIT applies an OR mask over this register, which means that bits will be set (-> OD function for given pins enabled)

Best Regards, Thorsten.