The customer is a Government of India Defense laboratory developing secure ASIC.
The customer developed a proprietary secure Microcontroller with only UART, Ethernet and a RAM like External Memory Interface (EMIF). Applications of the ASIC required additional interfaces such as NAND, USB Host, USB OTG and 1 Mbps UART. The final configuration needs 2x USB Host, 2x USB OTG, 2x NAND and 4x Full UART. A full USB Host and OTG stack with class drivers for storage (MSC) and USB-UART (CDC) were to be developed.
Challenges & Requirements:
1. The SoC did not have a full featured data sheet yet.
2. The GCC port for the SoC is functional but not fully validated.
3. Glue-logic was required to be developed between the EMIF and peripheral drivers and interrupts were required to be mapped to limited processor interrupts
4. A complete USB stack for Host and OTG with MSC and CDC Class drivers needs to be either ported or developed.
Thotakã designed a dual FPGA + SoC solution with COTS USB Host and OTG controllers to realize the design in a short span of 12 months. The U-boot USB stack was ported and substantially re-written to handle the class drivers. Significant amount of FPGA code was written to bridge the diverse peripheral interfaces with the External Memory Interface of the SoC. Test cases were developed to validated all the attached peripherals.
Benefits & Outcome:
1. Thotaka's SoC architecture team conversant with multiple processor architectures quickly understood the new SoC architecture and its instruction set and liaised with the ASIC developers and compiler teams for the start-up code.
2. Previous experience with USB interfaces helped in identifying a suitable Host and OTG controllers to be interfaced with the FPGA.
3. Thotakã’s bare-metal BSP team ported the U-boot USB stack alone to the new SOC and went ahead developing the MSC and CDC class drivers for both Host and OTG modes
4. The hardware team engineered a 14-layer board in a hand-held form-factor with full signal-integrity analysis in just 20 weeks.
5. The firmware engineering team not only discovered compiler bugs but worked with the compiler teams to fix them in time to ensure timely product delivery.
Thotakã delivered 20 pilot devices to the customer that satisfied all the specification within a span of 10 months.