USB Peripheral Controller John Jones 12/11/08 Embedded Systems Architecture

USB Peripheral Controller ARM USB CONTROLLER PHY USB Peripheral Device HOST

System Block Diagram Peripheral Controller ARM PHY Setup Data 8 bytes 4 IN Endpoints 128 bytes each 4 OUT Endpoints 128 bytes each ARM InterfacePHY Interface

SMSC USB3300 USB PHY Source: USB3300 datasheet

ARM & FPGA Development Board ARM Processor NXP LPC2132 Xilinx FPGA Spartan-3E X3CS500E

USB PHY Evaluation Board

Complete System

Interconnect

Problems… No external address and databus on ARM Only connection to FPGA is with P0.2 - P0.17. Could not get 8 continuous pins to form bus Some FPGA pins are dedicated inputs 3 port pins on the ARM were not functioning

Workaround… Bit Bang Port 0 I/O Access FPGA using a multiplexed address/data bus. Need to map and unmap bits to go around bad pins. unsigned int map_bits (unsigned int data) { unsigned int upper; unsigned int lower; unsigned int join; upper = (data & 0xF0) << 12; lower = (data & 0x0F) << 4; join = upper | lower; return join; } unsigned int unmap_bits (unsigned int data) { unsigned int upper; unsigned int lower; unsigned int join; upper = (data >> 12) & 0xF0; lower = (data >> 4) & 0x0F; join = upper | lower; return join; }

FPGA Write Function void fpga_wr(unsigned int address, unsigned int data) { unsigned int map_data; unsigned int map_addr; map_data = map_bits(data); map_addr = map_bits(address); IODIR0 = P0_OUTPUTS | P0_DATA; // Set BUS to output // Write address IOCLR0 = P0_LA|P0_RD|P0_WR|P0_DATA; // Initialize I/O IOSET0 = map_addr;// Drive Address IOSET0 = P0_LA;// Latch address // Write Data IOCLR0 = P0_LA|P0_RD|P0_WR|P0_DATA; // Initialize I/O IOSET0 = map_data;// Drive data IOSET0 = P0_WR;// Latch address IOCLR0 = P0_WR;// Negate WR IODIR0 = P0_OUTPUTS; // Tri-state Bus } 92 Assembly Instructions!

FPGA Read Function unsigned char fpga_rd(unsigned int address) { unsigned int map_addr; unsigned int raw_data, data; map_addr = map_bits(address); // Write address IODIR0 = P0_OUTPUTS | P0_DATA;// Set BUS to output IOCLR0 = P0_LA|P0_RD|P0_WR|P0_DATA;// Initialize I/O IOSET0 = map_addr;// Drive Address IOSET0 = P0_LA;// Latch Address IOCLR0 = P0_LA;// Negate IODIR0 = P0_OUTPUTS;// Tri-state Bus // Read Data IOSET0 = P0_RD;// Assert RD control raw_data = IOPIN0;// Latch data IOCLR0 = P0_RD;// Negate RD control data = unmap_bits(raw_data); return (unsigned char) data; } 90 Assembly Instructions!

USB Peripheral Controller Features… Four Endpoints 4 IN Buffers – 128 bytes each 4 OUT Buffers – 128 bytes each Setup Data Buffer Interrupt Start-of-frame, Setup Data, IN/OUT packets Shortcomings… No CRC support No double-buffering Manually toggle DATA0/DATA1

System Block Diagram Peripheral Controller ARM PHY Setup Data 8 bytes 4 IN Endpoints 128 bytes each 4 OUT Endpoints 128 bytes each ARM InterfacePHY Interface

ARM Interface

USB Controller

FPGA Registers IN0CNT, IN1CNT, IN2CNT, IN3CNT ARM writes to these registers to indicate how many bytes to transmit. OUT0CNT, OUT1CNT, OUT2CNT, OUT3CNT ARM reads these registers to determine how many bytes were received. IN_RDY – bits 3-0 ARM sets bit(s) to indicate if buffer has been transmitted. Set by ARM. Cleared by Controller. 1 – Buffer ready (waiting to be sent)0 – Buffer has been sent. Controller will NAK IN-packet requests to an endpoint buffer not ready. OUT_RDY – bits 3-0 ARM reads bit(s) to determine which buffer has new data. Set by Controller. Cleared by ARM. 1 – New data available,0 – No new data Controller will NAK OUT-packets if buffer has not been read by ARM (bit = 0).

FPGA Registers - continued IRQ Status Register ARM reads this register to determine source of interrupt. Four bits – four interrupt sources Bit 0 – Start-of-Frame Interrupt Bit 1 – Setup Data Available Bit 2 – IN Buffer Ready ARM must read IN RDY register to determine which buffer caused the interrupt. Bit 3 – OUT Buffer Ready ARM must read OUT RDY register to determine which buffer caused the interrupt. Write ‘1’ to clear

FPGA Registers - continued TOGGLE ARM must alternate DATA0 and DATA1 PID’s used for IN transactions. Four bits – one for each of the four IN buffers. Select which DATA PID to use for IN transactions. 0 – DATA0 PID 1 – DATA1 PID Device Address 0x00 on reset ARM re-programs this register after obtaining a new device address from host during the enumeration process. FRAME(HIGH) and FRAME(LOW) 11 bit frame number from SOF packets.

FPGA Registers - continued ULPI Address 6 bit address of USB3300 register to access. Refer to USB3300 datasheet. ULPI RW Bit 0 – ARM writes ‘1’ to initiate a write. Bit 1 – ARM writes ‘1’ to initiate a read. ULPI Data 8 bit read or write data.

Simulation – IN Transactions 1.ARM loads IN0, IN1, IN2, IN3 buffers. 2.ARM writes to byte count registers IN0CNT,…,IN3CNT. 3.ARM sets IN Ready Flags. 4.USB IN Transactions 1234

Simulation – IN Transaction (ZOOM)

Simulation – OUT Transactions 1.USB SETUP Packet 2.USB OUT transactions to endpoints 0, 1, 2, 3. 3.ARM reads Setup Data and OUT0, OUT1, OUT2, OUT3 buffers. 132

Simulation – OUT Transactions (zoom)

Start-of-Frame Packets “phy_dir” “phy_nxt” “Rx_Active” “SOF Detect” RXCMD updates BYTE 1BYTE 2BYTE 3

Start-of-Frame Packet Interval 1 millisecond

Setup Transaction “new_data” “Rx Active” “Start of Frame” “IRQ” SOF Packet SETUP Packet Setup Data (11bytes): PID + 8 bytes + CRC16

Setup Data ByteValueDescription 00x80bmRequestType 10x06 Get Descriptor 20x00 30x01Device 40x00 50x00 60x40Number of bytes 70x00 Screen capture from Insight (GUI for GNU GDB)

Device Descriptor unsigned char DeviceDescriptor[] = { 18,// Length 1,// Type 0x10,1,// USB Rev 1.1 (=0110H,low=10H, High=01H) 0,// Class 0,// Subclass 0,// Protocol 64,// Maximum Packet Size 0x42, 0x42,// Vendor ID 1, 0x42, 0, 1,// Product ID and Version 1, 2, 0,// Manufacturer, Product & Serial# Names 1// #Configs };

ARM Interrupt Handling void IRQ_Service(void) { if ( VICIRQStatus & 0x ) TMR1_Service(); if ( VICIRQStatus & 0x ) TMR0_Service(); } /********************************************/ /* Vector table and reset entry */ /********************************************/ _vectors: ldr pc, ResetAddr /* Reset */ ldr pc, UndefAddr /* Undefined instruction */ ldr pc, SWIAddr /* Software interrupt */ ldr pc, PAbortAddr /* Prefetch abort */ ldr pc, DAbortAddr /* Data abort */ ldr pc, ReservedAddr/* Reserved */ ldr pc, IRQAddr /* IRQ interrupt */ ldr pc, FIQAddr /* FIQ interrupt */ : IRQAddr:.word IRQHandler FIQAddr:.word FIQHandler : IRQHandler: stmdb sp!, {r0-r12, lr}/* save all registers */ bl IRQ_Service ldmia sp!, {r0-r12, lr} /* restore all registers */ subs pc, lr, #4/* Restore CPSR and return */ Assembly Code C-code