Hello! I'm glad to present my project here. Project is some years old, may be you know. Free, powerful flash and mcu programmer, now has support for eMMC on arduino-based hardware.
Now I post link to russian forum only, but I will describe thoroughly soon all aspects. Please, give me a time.
Project's home is here:
https://monitor.net.ru/forum/threads/317755/***
Some explained in Postal3_USBprog_sources_old.rar (old, check mistake on sda-scl pins, may be reverted)
fuses for Mega8: High=CF, Low=AF;
fuses for Mega88-168-328: Ext=FD, High=DD, Low=E7.
***
For eMMC support need short connection:
PB2(SS) to PD5 and PB5(SCK) to PD6. (on AtMega, see datasheet for pinout)
And connection to eMMC:
MOSI=>CMD, MISO=>DAT0, SCK=>SCK
And must be 10k pull-up for CMD,DAT0 and pull-down for SCK.
Begin with "SetISP" button.
***
Current firmware for eMMC support is postalavr_v4c.rar
Current software Postal3_emmc_v7.rar
Drivers must be last usbXpress for CP2102 (need SiUSBXp.dll from driver's package)
***
Try!