samples: boards: stm32 mco output control

This samples enables and configure the MCO1/2 output for stm32 target boards. Signed-off-by: Francois Ramu <[email protected]>
zephyrproject-rtos · Nov 15, 2024 · 3603ce3 · 3603ce3
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diff --git a/samples/boards/st/mco/README.rst b/samples/boards/st/mco/README.rst
@@ -16,6 +16,11 @@ Requirements
 The SoC should support MCO functionality and use a pin that has the MCO alternate function.
 To support another board, add a dts overlay file in boards folder.
 Make sure that the output clock is enabled in dts overlay file.
+Depending on the stm32 serie, several clock source are possible for each MCOx and prescaler.
+The clock source is set by the DTS and converted in LL_RCC_MCO2SOURCE_xxx which is the parameter
+for the LL_RCC_ConfigMCO function.
+If prescaler is set by the DTS, the property prescaler = <5>; will be converted in LL_RCC_MCO2_DIV_5
+which is the parameter for the LL_RCC_ConfigMCO function.
 
 
 Building and Running

diff --git a/samples/boards/st/mco/boards/nucleo_f411re.overlay b/samples/boards/st/mco/boards/nucleo_f411re.overlay
@@ -0,0 +1,18 @@
+/* Enable the PLLI2s and set it as clock source for the MCO2 (with prescaler 5) */
+
+&plli2s {
+	div-m = <8>;
+	mul-n = <100>;
+	div-r = <2>;
+	clocks = <&clk_hse>;
+	status = "okay";
+};
+
+/* see RefMan RM0383 */
+&mco2 {
+	clocks = <&rcc STM32_SRC_PLLI2S_R MCO2_SEL(1)>;
+	prescaler = <5>; /* set 0b111 in the MCO2PRE of the RCC CFGR */
+	pinctrl-0 = <&rcc_mco_2_pc9>;
+	pinctrl-names = "default";
+	status = "okay";
+};
diff --git a/samples/boards/st/mco/boards/nucleo_u5a5zj_q.overlay b/samples/boards/st/mco/boards/nucleo_u5a5zj_q.overlay
@@ -16,7 +16,7 @@
 &mco1 {
 	status = "okay";
 	clocks = <&rcc STM32_SRC_LSE MCO1_SEL(MCO1_SEL_LSE)>;
-	prescaler = <MCO1_PRE(MCO1_PRE_DIV_2)>;
+	prescaler = <MCO1_PRE_DIV_2>;
 	pinctrl-0 = <&rcc_mco_pa8>;
 	pinctrl-names = "default";
 };
diff --git a/samples/boards/st/mco/boards/stm32f746g_disco.overlay b/samples/boards/st/mco/boards/stm32f746g_disco.overlay
@@ -38,7 +38,7 @@
 &mco2 {
 	status = "okay";
 	clocks = <&rcc STM32_SRC_HSE MCO2_SEL(MCO2_SEL_HSE)>;
-	prescaler = <MCO2_PRE(MCO2_PRE_DIV_5)>;
+	prescaler = <MCO2_PRE_DIV_5>;
 	pinctrl-0 = <&rcc_mco_2_pc9>; /* uSD_D1 (CN3 pin 8) */
 	pinctrl-names = "default";
 };
diff --git a/samples/boards/st/mco/src/main.c b/samples/boards/st/mco/src/main.c
@@ -17,13 +17,15 @@ int main(void)
 	 * initialization. This sample checks that all MCOs are ready - if so,
 	 * the selected clock should be visible on the chosen GPIO pin.
 	 */
+#if DT_NODE_HAS_STATUS_OKAY(DT_NODELABEL(mco1))
 	dev = DEVICE_DT_GET(DT_NODELABEL(mco1));
 	if (device_is_ready(dev)) {
 		printk("MCO1 device successfully configured\n");
 	} else {
 		printk("MCO1 device not ready\n");
 		return -1;
 	}
+#endif /* mco1 */
 
 #if DT_NODE_HAS_STATUS_OKAY(DT_NODELABEL(mco2))
 	dev = DEVICE_DT_GET(DT_NODELABEL(mco2));
@@ -33,7 +35,7 @@ int main(void)
 		printk("MCO2 device not ready\n");
 		return -1;
 	}
-#endif
+#endif /* mco2 */
 
 	printk("\nDisplayed the status of all MCO devices - end of example.\n");
 	return 0;