How must the SD card be formatted correctly? I try to use a new SD card, but always get the red-red-red sequence. The following messages are shown via the serial port:
SD initialized.
6/23/18 14:57:15z Real Time Clock is running. Unix time 1529765835
6/23/18 14:57:15z Version 02_03_08
6/23/18 14:57:15z Reset reason: External System
6/23/18 14:57:15z Trace: 15:1, 15:0, 15:1, 15:1, 15:0, 15:1, 15:1, 15:0, 15:1, 15:1, 15:0, 15:1, 15:1, 15:0, 15:1, 11:7, 11:8, 16:0, 11:8, 11:9, 1:1, 9:0, 8:4, 8:6, 8:8, 8:4, 8:6, 8:8, 1:2, 1:3, 1:4, 1:5
6/23/18 14:57:15z ESP8266 ChipID: 2329763
6/23/18 14:57:15z Local time zone: 0
6/23/18 14:57:15z device name: IotaWatt, version: 3
6/23/18 14:57:16z MDNS responder started
6/23/18 14:57:16z You can now connect to http://IotaWatt.local
6/23/18 14:57:16z HTTP server started
6/23/18 14:57:16z dataLog: service started.
mkdir failed: /IotaWatt
6/23/18 14:57:16z dataLog: Log file open failed. 2
6/23/18 14:57:16z Program halted.
I used the following tool to format the new card: SD Memory Card Formatter | SD Association
I copied the files at IoTaWatt/SD at master · boblemaire/IoTaWatt · GitHub to the top level of the SD card.
Is there anything else to consider?
UPDATE Solved, formatting with FAT16 was the solution. Mac users have a look here: Formatting FAT16 under Mac OSX - adafruit industries