Hardware

Hardware 

Specifications

• 15 bit color
• 1 user button
• stereo 12bit DAC
• microSD driven by 4wire SDIO
• 2 USB 2.0 host
• 1 microUSB for power
• UEXT extension port

Hardware Reference (for kernel coding)

• User Button : PE15
• use pullUP, set to GND when pressed
• User LED : PA2
• VGA : 
• H Sync : PA1
• V Sync : PA0
• R : PE14-10
• G : PE 9-5
• B : PE 4-0
• Main CPU frequency is 192MHz now. This means that a full screen range can be 700x480 (generated as 640x480, sync taken care by screens)
• Audio :  
• L : PA4, R : PA5
• lowpass filter
• Boot : 
• Boot1 : pulled down, 
• Boot0 : pulled down, jumper up

• SDIO
• SDIO 4pins used.
• std SDIO pins, no pullup (use internal pullups)
• Card sense on PC7 (no ext pullup, setup internal) ; set to GND if card present (see errata)
• Dual USB host 
• std pins
• Micro USB : used for power.
• 500mA power polyfuse
• Can be used for full USB (even usb device w/ DFU) in place of USB HOST x using solder jumpers
• Pullups (47k) on : 
• PC11, PA10,PB5, PB11 (boot1)
• UEXT 10-pins connector using
• USART3 (TX/RX, no DFU), or PD8&9 
• I2C1 (PB6/7)
• SPI (PB9,10 /  PC2,3)
• Swd 4 pins, requires power

Schematics, PCB : available on github

 

Rev2a ERRATA

- The SDIO sense had a bad connexion to GND (cards seems to always be on).
Effect : SDIO card is always reported be present.
Workaround : This can be manually fixed by cutting a wire & rewiring gnd to nearby SWD by example.
Fixed : rev2b

- The Vref+ pin 21 was not put to VCC.
Effect : Sound does not work.
Workaround : solder to next pin 22 (vdda)
Fixed : rev2b