diff -r 000000000000 -r b74b0e4902c3 main/task_sdcard.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main/task_sdcard.h	Sat Oct 20 13:23:15 2018 +0200
@@ -0,0 +1,80 @@
+#ifndef	_TASK_SDCARD_H
+#define	_TASK_SDCARD_H
+
+/**
+ * @file task_sdcard.h
+ * @brief The interface to the FreeRTOS SD/MMC card task.
+ */
+
+
+typedef enum
+{
+    ANNOTATION_STAGE = 0,		///< Annotate stage event
+    ANNOTATION_EVENT,			///< Annotate an event
+    ANNOTATION_SYSTEM,			///< Annotate a system event.
+} ANNOTATION_TYPES;
+
+/**
+ * @brief Structure containing the information of the SD cards task.
+ */
+typedef struct {
+    bool	host_ok;		///< SPI host is Ok.
+    bool	card_present;		///< If card is present in the slot.
+    char	logfile[32];		///< Current logfile name.
+} SDCARD_State;
+
+/**
+ * @brief JSON log data
+ */
+typedef struct {
+    char	time[9];		///< Time in the brew.
+    float	mlt_sp;			///< MLT setpoint.
+    float	mlt_pv;			///< MLT temperature.
+    int		mlt_power;		///< MLT power in %
+    int		mlt_tempreached;	///< MLT temperature reached (0 or 1).
+    int		pump_run;		///< Pump run (0 or 1).
+    float	hlt_sp;			///< HLT setpoint.
+    float	hlt_pv;			///< HLT temperature.
+    int		hlt_power;		///< HLT power in %.
+    char	event[64];		///< Event message.
+} JSON_log;
+
+/**
+ * @brief Begin a new logfile. The logfile is created and written to on
+ *        the spiffs filesystem.
+ * @param t The time in seconds since the Epoch, to create the filename.
+ */
+void log_begin(time_t t);
+
+/**
+ * @brief Close an open logfile. The logfile is moved to the SD card if
+ *        the card is present and mounted. Then, the temporary logfile
+ *        is removed.
+ */
+void log_close(void);
+
+/**
+ * @brief Clean logfile directory /spiffs/log/
+ */
+void log_clean(void);
+
+/**
+ * @brief Log to JSON logfile.
+ */
+void log_json(void);
+
+/**
+ * @brief Log annotations for the chart. These are stored in a temporary 
+ *        file and later when the logfile is closed they are merged in 
+ *        the main json logfile.
+ * @param annotation_type The type of annotation, stage/event/system.
+ * @param label The label text that will be seen in the chart.
+ */
+void log_annotation(int annotation_type, char *label);
+
+/**
+ * @brief FreeRTOS sd card task. 
+ */
+void task_sdcard(void *);
+
+#endif