diff options
| -rw-r--r-- | src/cc1111/ao_timer.c | 31 |
1 files changed, 27 insertions, 4 deletions
diff --git a/src/cc1111/ao_timer.c b/src/cc1111/ao_timer.c index 75cc4ce8..d681f51b 100644 --- a/src/cc1111/ao_timer.c +++ b/src/cc1111/ao_timer.c @@ -83,25 +83,48 @@ ao_timer_init(void) T1CTL = T1CTL_MODE_MODULO | T1CTL_DIV_8; } +static void +ao_clock_delay(void) +{ + uint16_t i = 0; + + while (--i) + ao_arch_nop(); +} + /* * AltOS always cranks the clock to the max frequency */ void ao_clock_init(void) { - /* Switch system clock to crystal oscilator */ - CLKCON = (CLKCON & ~CLKCON_OSC_MASK) | (CLKCON_OSC_XTAL); + /* Power up both oscillators */ + SLEEP &= ~(SLEEP_OSC_PD); - while (!(SLEEP & SLEEP_XOSC_STB)) + /* Switch to the HFRC oscillator */ + CLKCON = (CLKCON & ~CLKCON_OSC_MASK) | (CLKCON_OSC_RC); + + /* Wait for the HFRC oscillator to be stable */ + while (!(SLEEP & SLEEP_HFRC_STB)) ; + /* Delay for 'a while' waiting for the crystal to + * stabilize -- the XOSC_STB bit isn't reliable + * + * http://www.ti.com/lit/er/swrz022c/swrz022c.pdf + */ + + ao_clock_delay(); + + /* Switch system clock to crystal oscilator */ + CLKCON = (CLKCON & ~CLKCON_OSC_MASK) | (CLKCON_OSC_XTAL); + /* Power down the unused HFRC oscillator */ SLEEP |= SLEEP_OSC_PD; /* Wait for HFRC to power down */ while ((SLEEP & SLEEP_HFRC_STB) != 0) ; - /* Crank up the timer tick and system clock speed */ CLKCON = ((CLKCON & ~(CLKCON_TICKSPD_MASK | CLKCON_CLKSPD_MASK)) | (CLKCON_TICKSPD_1 | CLKCON_CLKSPD_1)); |