diff --git a/doc/source/firmware/safety.rst b/doc/source/firmware/safety.rst
index ba22094..5a7d945 100644
--- a/doc/source/firmware/safety.rst
+++ b/doc/source/firmware/safety.rst
@@ -13,7 +13,7 @@ On the other hand, fatal errors like an over-temperature error, or memory proble
 which forces the output zero, but does not allow any further interaction.
 
 .. toctree::
-	:maxdepth: 2
+	:maxdepth: 3
 	
 	flags
 	backup-ram
diff --git a/stm-firmware/Makefile b/stm-firmware/Makefile
index 67b2f40..88cab6d 100644
--- a/stm-firmware/Makefile
+++ b/stm-firmware/Makefile
@@ -46,7 +46,7 @@ CFILES += ui/lcd.c ui/menu.c reflow-menu.c
 CFILES += fatfs/diskio.c fatfs/ff.c fatfs/ffsystem.c fatfs/ffunicode.c fatfs/shimatta_sdio_driver/shimatta_sdio.c
 CFILES += pid-controller.c oven-driver.c
 CFILES += settings/settings.c settings/settings-sd-card.c
-
+CFILES += stm-periph/crc-unit.c
 CFILES += safety/safety-adc.c safety/safety-controller.c safety/watchdog.c safety/fault.c safety/safety-memory.c
 
 DEBUG_DEFINES = -DDEBUGBUILD
diff --git a/stm-firmware/include/reflow-controller/safety/safety-memory.h b/stm-firmware/include/reflow-controller/safety/safety-memory.h
index 1f8a43a..cbfacd5 100644
--- a/stm-firmware/include/reflow-controller/safety/safety-memory.h
+++ b/stm-firmware/include/reflow-controller/safety/safety-memory.h
@@ -52,5 +52,4 @@ struct safety_memory_boot_status {
 	uint32_t code_updated;	
 };
 
-
 #endif /* __SAFETY_MEMORY_H__ */
diff --git a/stm-firmware/include/stm-periph/crc-unit.h b/stm-firmware/include/stm-periph/crc-unit.h
new file mode 100644
index 0000000..b9b5158
--- /dev/null
+++ b/stm-firmware/include/stm-periph/crc-unit.h
@@ -0,0 +1,38 @@
+/* Reflow Oven Controller
+ *
+ * Copyright (C) 2020  Mario Hüttel <mario.huettel@gmx.net>
+ *
+ * This file is part of the Reflow Oven Controller Project.
+ *
+ * The reflow oven controller is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * GDSII-Converter is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with the reflow oven controller project.
+ * If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef __CRC_UNIT_H__
+#define __CRC_UNIT_H__
+
+#include <stdint.h>
+
+void crc_unit_init(void);
+
+void crc_unit_deinit(void);
+
+void crc_unit_reset(void);
+
+uint32_t crc_unit_get_crc(void);
+
+void crc_unit_input(uint32_t data);
+
+void crc_unit_input_array(const uint32_t *data, uint32_t len);
+
+#endif /* __CRC_UNIT_H__ */
diff --git a/stm-firmware/stm-periph/crc-unit.c b/stm-firmware/stm-periph/crc-unit.c
new file mode 100644
index 0000000..672315b
--- /dev/null
+++ b/stm-firmware/stm-periph/crc-unit.c
@@ -0,0 +1,59 @@
+/* Reflow Oven Controller
+ *
+ * Copyright (C) 2020  Mario Hüttel <mario.huettel@gmx.net>
+ *
+ * This file is part of the Reflow Oven Controller Project.
+ *
+ * The reflow oven controller is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * GDSII-Converter is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with the reflow oven controller project.
+ * If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <stm-periph/crc-unit.h>
+#include <stm-periph/clock-enable-manager.h>
+#include <stm32/stm32f4xx.h>
+
+void crc_unit_init(void)
+{
+	rcc_manager_enable_clock(&RCC->AHB1ENR, BITMASK_TO_BITNO(RCC_AHB1ENR_CRCEN));
+	crc_unit_reset();
+}
+
+void crc_unit_deinit(void)
+{
+	rcc_manager_disable_clock(&RCC->AHB1ENR, BITMASK_TO_BITNO(RCC_AHB1ENR_CRCEN));
+}
+
+void crc_unit_reset(void)
+{
+	CRC->CR = CRC_CR_RESET;
+}
+
+uint32_t crc_unit_get_crc(void)
+{
+	return CRC->DR;
+}
+
+void crc_unit_input(uint32_t data)
+{
+	CRC->DR = data;
+}
+
+void crc_unit_input_array(const uint32_t *data, uint32_t len)
+{
+	uint32_t i;
+
+	if (!data)
+		return;
+	for (i = 0; i < len; i++)
+		crc_unit_input(data[i]);
+}