comment generic clock supplier for samd21

Signed-off-by: dylad <dylan.laduranty@mesotic.com>
RIOT-OS · Sep 5, 2017 · f92daff · f92daff
1 parent f8624bd
commit f92daff
Showing 1 changed file with 2 additions and 0 deletions.
diff --git a/cpu/sam0_common/periph/gpio.c b/cpu/sam0_common/periph/gpio.c
@@ -128,6 +128,8 @@ int gpio_init_int(gpio_t pin, gpio_mode_t mode, gpio_flank_t flank,
 #ifdef CPU_FAM_SAMD21
     /* enable clocks for the EIC module */
     PM->APBAMASK.reg |= PM_APBAMASK_EIC;
+    /* SAMD21 used GCLK2 which is supplied by either the ultra low power
+       internal or external 32 kHz */
     GCLK->CLKCTRL.reg = (EIC_GCLK_ID |
                          GCLK_CLKCTRL_CLKEN |
                          GCLK_CLKCTRL_GEN_GCLK2);