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Atmel RF: use system wait_ns #10144

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Merged
merged 1 commit into from
Mar 21, 2019
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Atmel RF: use system wait_ns #10144

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67 changes: 1 addition & 66 deletions components/802.15.4_RF/atmel-rf-driver/source/NanostackRfPhyAtmel.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -321,75 +321,10 @@ static void rf_if_ack_timer_signal(void)
}
#endif

// *INDENT-OFF*
/* Delay functions for RF Chip SPI access */
#ifdef __CC_ARM
__asm static void delay_loop(uint32_t count)
{
1
SUBS a1, a1, #1
BCS %BT1
BX lr
}
#elif defined (__ARMCC_VERSION) /* ARMC6 */
void delay_loop(uint32_t count)
{
// TODO: This needs implementation
while(count--)
;;
}
#elif defined (__ICCARM__)
static void delay_loop(uint32_t count)
{
__asm volatile(
"loop: \n"
" SUBS %0, %0, #1 \n"
" BCS.n loop\n"
: "+r" (count)
:
: "cc"
);
}
#else // GCC
static void delay_loop(uint32_t count)
{
__asm__ volatile (
"%=:\n\t"
#if defined(__thumb__) && !defined(__thumb2__)
"SUB %0, #1\n\t"
#else
"SUBS %0, %0, #1\n\t"
#endif
"BCS %=b\n\t"
: "+l" (count)
:
: "cc"
);
}
#endif
// *INDENT-ON*

static void delay_ns(uint32_t ns)
{
uint32_t cycles_per_us = SystemCoreClock / 1000000;
// Cortex-M0 takes 4 cycles per loop (SUB=1, BCS=3)
// Cortex-M3 and M4 takes 3 cycles per loop (SUB=1, BCS=2)
// Cortex-M7 - who knows?
// Cortex M3-M7 have "CYCCNT" - would be better than a software loop, but M0 doesn't
// Assume 3 cycles per loop for now - will be 33% slow on M0. No biggie,
// as original version of code was 300% slow on M4.
// [Note that this very calculation, plus call overhead, will take multiple
// cycles. Could well be 100ns on its own... So round down here, startup is
// worth at least one loop iteration.]
uint32_t count = (cycles_per_us * ns) / 3000;

delay_loop(count);
}

// t1 = 180ns, SEL falling edge to MISO active [SPI setup assumed slow enough to not need manual delay]
#define CS_SELECT() {rf->CS = 0; /* delay_ns(180); */}
// t9 = 250ns, last clock to SEL rising edge, t8 = 250ns, SPI idle time between consecutive access
#define CS_RELEASE() {delay_ns(250); rf->CS = 1; delay_ns(250);}
#define CS_RELEASE() {wait_ns(250); rf->CS = 1; wait_ns(250);}

/*
* \brief Read connected radio part.
Expand Down