How do I write/read raw from an SD card.

I do not want fat, ufat, fat16...

Building up a simple weather station. The weather station will upload its data with a GSM modem (cell phone) once a week. I need 128K of local storage a day. About 1MB a week.

Figured an SD card would be the simplest. The card will be soldered in place. I never want to have to service the station, unless the card burns out from old age. I am after a few simple function. card_size all_zeros write all zeros to blank the card. write read

Thats it. I have no problems doing most of the code. I just help writing the card access part of the code. From there I can write the other functions I need. Ideas?

The card will be soldered in place. I never want to have to service the station

What's the purpose of logging the data if you never intend to remove the card?

Why can't you borrow the bits you need from one of the existing libraries that provides more functionality than you think you need?

The weather station will upload its data with a GSM modem