From c7e334d3dcbd1c33de6bc971ba96b8efa4b1e5e5 Mon Sep 17 00:00:00 2001
From: Steffen Pengel <steffen.pengel@gmail.com>
Date: Sun, 9 Apr 2017 15:06:43 +0200
Subject: [PATCH] cpu/stm32f3: set i2c clk input to sysclk when HSI is
deactivated
According to the STM32F3 clocktree (ref. manual p. 126) the I2CX
hardware is driven by either HSI or SYSCLK.
If HSI is deactivated SYSCLK clock must be selected as I2CX clock.
Signed-off-by: Steffen Pengel <steffen.pengel@gmail.com>
---
cpu/stm32f3/cpu.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/cpu/stm32f3/cpu.c b/cpu/stm32f3/cpu.c
index 66bb7763a7..e6f99ece3e 100644
--- a/cpu/stm32f3/cpu.c
+++ b/cpu/stm32f3/cpu.c
@@ -140,5 +140,15 @@ static void cpu_clock_init(void)
/* disable the HSI if we use the HSE */
RCC->CR &= ~(RCC_CR_HSION);
while (RCC->CR & RCC_CR_HSIRDY) {}
+
+ /* swith I2Cx clock source to SYSCLK */
+ RCC->CFGR3 &= ~(RCC_CFGR3_I2CSW);
+ RCC->CFGR3 |= RCC_CFGR3_I2C1SW_SYSCLK;
+#ifdef RCC_CFGR3_I2C2SW_SYSCLK
+ RCC->CFGR3 |= RCC_CFGR3_I2C2SW_SYSCLK;
+#endif
+#ifdef RCC_CFGR3_I2C3SW_SYSCLK
+ RCC->CFGR3 |= RCC_CFGR3_I2C3SW_SYSCLK;
+#endif
#endif
}
--
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