Finally back to work on my Beaglebone LCD cape project. Yes both the Optrex 5 inch and the Newhaven 3.5 inch displays are running. I display all graphics using SDL and the directFB driver (no X involved).
Rev A of the LCD-IO Expansion Cape is running (mostly). I screwed up the CAM job when I sent the gerbers into the board house. Some inner power traces were missing, but I was able to work around that. Needless to say, Rev B is being built this week. I was able to verify all the components worked as designed and that the cape mated with the Beaglebone correctly. No pictures of the completed Rev A hacked up board, but I will post images of the Rev B cape populated and running on a Beaglebone with both the Optrex 5 inch 800×480 and the Newhaven 3.5 inch 320×240 displays. I am using the basic Angstrom distribution and customizing the pin muxing in the board file for 24 bit color, SPI0 and SPI1, UART1 and UART4. In the upper right corner of the image of the cape, the 8 pin socket is for the AT24CP EEPROM and it is recognized during boot.
In the lower left side of the image (to the right of the Ethernet connector cutout) is where the coin cell battery holder is located (bottom side of board). This battery is used to keep the NXP PCF2127A RTCC alive when power is removed from the system. The RTCC is located in the lower right corner. All UART signals and GPIO from the Beaglebone and PIC are routed to 2mm connectors on the board and to the DB25 Female connector seen in the image top left next to the 8 pin dip where the EEPROM is located. The board dimensions are such that it fits into a custom aluminum extrusion with slots on the inside where the cape will snuggly slide into. The Beaglebone is then carried by the Cape inside this enclosure.
Gerbers for my 1st BeagleBone Cape went to the board house yesterday (12/15/11), received word this afternoon the files were without error and processing has begun. Should be ready by Thursday next week and in my hands ready for assembly the day after Christmas. This Cape is a generic LCD TFT display and IO expander board. It has one of the new Microchip PIC32MX120F032D chips used as an auxiliary processor for IO and communicates with the BeagleBone via SPI. In addition, a NXP PCF2127 RTCC with battery backup is installed and communicates with the PIC(tm) via I2C.
Overview of capabilities:
- 80 pin TQFP package
- 144K Flash
- 8192 Bytes SRAM
- 4096 Bytes EEPROM
- 5 each 16 Bit Timers
- 12 Bit A/D
- 2 each UARTS
- 2 each SPI
- 1 each I2C
- 2 each CAN
Both UARTS on the PIC are brought out to DB 9 connectors on the expansion board. In addition, via jumper selection, the input and output of both UARTS can be routed through RS422 or RS232 driver chips.
One of the SPI modules is dedicated to communications with the OMAP on the Beagleboard. The other SPI module is connected to a on board MRF24J40MB2.4 GHz IEEE 802.15.4 Transceiver Module and an on board LIS331DLH 3 axis accelerometer.
The I2C module is connected to an NXP PCF2127A Real Time Clock Calendar module with battery backup. The 32.768Khz output from the RTCC is feed back to the dsPIC30F6014A’s SOSCI pin to provide a clock pulse for the internal RTCC.
The dsPIC30F6014A’s OC3 is feed to an LT3465 which is used to drive the LED backlights on the external LCD/TFT display. In addition OC4 is feed to the base of a MMBT3904 NPN transistor which can be used to control external LEDs.
Analog channels AN8 and AN9 are brought out to connectors which an be used to connect Potentiometers to. This can be used to control the PWM outputs of OC3 and OC4 which allows an external user control of the brightness of the connected LEDs.
Additional analog input, pwm output, input capture pins are brought out to connectors for various devices.
CAN bus 1 is feed into an MCP2551 CAN Transceiver for connection to a CAN bus.
This blog will be dedicated to my development efforts using both the standard Beagleboard and the Beagleboard xM. The goal of this blog is to describe both my hardware and software development cycles in bringing a general purpose expansion board to life. This expansion board brings out a majority of the subsystems found on the Beagleboard and translates them to both 5v and 3.3v signal levels. In addition, the expansion board brings out all the display signals to a generic RGB TFT-LCD connector. The expansion board contains a Microchip dsPIC30F6014A microcontroller which communicates with the Beagleboard via the OMAP’s SPI3 interface.