Logging to SD-card

Logging happens in (space-and-time-saving) binary format, via the SPI protocol. Most MMC cards do not support SPI protocol. All SD-cards should support SPI (according to the standard specification), but we found that some (eg. some Maxwell) actually does not support it. It is safe to try, does no damage.

See for usage.

Where can interface card be purchased? It is not on the WebShop.

- Gunni - Yes it is in the webshop


GenBoard/VerThree supports logging to SD-card plugged to the "ISPI header". which was designed for this. (the same header is available since v3.0).

SD-Card is normally NOT removable (different cardholder-daughterboard and blind endplate is used), but installed permanently inside the case. Overview data can be downloaded very quickly via RS232 port. Selected files (each startup of the engine is logged to different file) or selected parts can be downloaded (appr 1 min download time / 10 min log).

Some installers sometimes choose removable SD-card (with appropriate endplate)


Advantage: can be swapped with another (erased to full-00 earlier). This is not recomnmended, as viewing the data from a card removed from the controller (especially when cardreader is connected to windows PC) currently requires more steps (data can be read to binary file with dd command and formatted to csv by VemsTune). Probably only useful when logged data to download at a time exceeds 200 logged minutes.


GPS logging

Logging happens in binary format, via the SPI protocol.

See for usage.

Old thoughts:

For onboard logging (GenBoard/VerThree) we considered the SPI atmel flashes that appear MMC SPI-mode compatible:

Real MMC is basically the same electrical interface and protocol, but more available and can be removed if a socket is used.


Working system with MMC and ATmega161:

Flashfile C library for MMC/SD FAT

Procyon AVRlib with MMC, FAT, IP, graphic lcd support and lots more

Basic tech info about hw & sw interface system

Hitachi 16MB MMC-DataSheet as Sample

Detailed MMC spec: 130 pages]


Tech sheets

MMC and SD sources

Can someone check these Toshiba SD flash and comment on them? The question is if we can talk to it via SPI.

We would host in WebShop if suitable. Other type is OK, but we want to make sure to be fully compatible with our firmware and HW.

That aside, they are drivable through SPI (sure?)

Official doco appears to need licensed, but there's some limited info here -

MMC sockets

also digikey has some sockets from HRC

hr845ct-nd $3.80

hr846ct-nd $3.80

Note that the MMC and SD have 7 pins with standard 2.54mm centerline so any card-edge connector should work. Your old 286 ISA motherboard comes to mind with a hammer in the background :-)

Steps to make it work in SPI mode

AVR side

PC app

Future options

See also

Questions about SD Card logging (21-05-2013)

- Does the log on the sdcard contain config and table information? Now i need to load a config in vemstune to be able to load a log from sd. Would be nice if config is in the log. That way you always know which setup was used when log is created. Like when you log with laptop.

- Is it possible to log to sd card with greater speed than 10hz?

- Is it possible to start/stop logging to sd card using an input / switch?

- Would be cool if vems had a realtime clock. So the logfile have "real" date and time information.

- I think all these things would help if vems is used with a race car.