HackRF
25.1.1 Jiggle SGPIO Pins From GPIO Mode
My first test was to ensure I had the right pin(s) hooked up to my scope:
// Jiggle one of the SGPIO pins in GPIO mode, to make sure
// I'm looking at the right pin on the scope.
scu_pinmux(9, 0, MD_PLN_FAST, 0);
GPIO_SetDir(4, 1L << 12, 1);
while(1) {
volatile int i;
GPIO_SetValue(4, 1L << 12);
for(i=0; i<1000; i++);
GPIO_ClearValue(4, 1L << 12);
for(i=0; i<1000; i++);
}
25.1.2 Jiggle Pins from SGPIO Mode
You can also control SGPIO pins, GPIO-style, from within the SGPIO peripheral. This helped me understand the
basics of operating the SGPIO output mux.
// Set pin to SGPIO mode, toggle output using SGPIO
// peripheral registers.
scu_pinmux(9, 0, MD_PLN_FAST, 6); // SGPIO0
// P_OUT_CFG = 4, gpio_out
// P_OE_CFG = X
LPC_SGPIO->OUT_MUX_CFG[0] = (0L << 4) | (4L << 0);
LPC_SGPIO->GPIO_OENREG |= (1L << 0);
while(1) {
volatile int i;
LPC_SGPIO->GPIO_OUTREG |= (1L << 0);
for(i=0; i<1000; i++);
LPC_SGPIO->GPIO_OUTREG &= ~(1L << 0);
for(i=0; i<1000; i++);
}
25.1.3 Serializing Data With Slice Clock Source
My first full-on SGPIO experiment involved serializing a data pattern from slice A, using slice D to generate a SG-
PIO_CLK/2 data rate. I derived the code from examples that configured the SGPIO as I2S interfaces:
// Disable all counters during configuration
LPC_SGPIO->CTRL_ENABLED = 0;
// Configure pin functions.
scu_pinmux(9, 0, MD_PLN_FAST, 6); // SGPIO0
scu_pinmux(2, 3, MD_PLN_FAST, 0); // SGPIO12
(continues on next page)
96 Chapter 25. LPC4350 SGPIO Experimentation
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