링크를 찾아가서 보면 will read frequently를 true 로 설정해주면 최적화 된다고 하는데
TheCanvasRenderingContext2Dobject also has awill read frequentlyboolean. When aCanvasRenderingContext2Dobject'swill read frequentlyis true, the user agent may optimize the canvas for readback operations. On most devices the user agent needs to decide whether to store the canvas'soutput bitmapon the GPU (this is also called "hardware accelerated"), or on the CPU (also called "software"). Most rendering operations are more performant for accelerated canvases, with the major exception being readback withgetImageData(),toDataURL(), ortoBlob().CanvasRenderingContext2Dobjects withwill read frequentlyequal to true tell the user agent that the webpage is likely to perform many readback operations and that it is advantageous to use a software canvas.
어디다가 저걸 넣어야 하나 해서 따라가보니 getContext("2d")로 끝낼게 아니라, 초기화 옵션으로 주면 되는 듯.
Part No: FT2232HQ USB Hi-Speed to Dual Channel Serial UART/FIFO/JTAG/SPI/I2C IC, QFN-64 Hi-speed USB 2.0 Slave to Dual Channel UART / Serial Converter
Data Rates: 12Mbaud (UART) up to 40MB/s (Sync FIFO) USB Transfer Modes: Bulk Interfaces: UART, FIFO, 2 x MPSSE, Fast serial, 8051 MCU emulation, 16 GPIOs USB Host: No Packages: 64-pin QFN Channels: 2 I/O Voltage: 3.3V USB Class: Vendor Virtual Com Port: Yes Operating Temperature: -40°C to +85°C Standard Price (Easy checkout) Order Quantity Price per Unit 1 - 9 : USD5.10 10 - 49 : USD4.90 50 - 99 : USD4.80 100 - 249 : USD4.70 250 - 499 : USD4.50 500 - 999 : USD4.25
Key Hardware Features Single chip USB to dual serial / parallel ports with a variety of configurations. Entire USB protocol handled on the chip. No USB specific firmware programming required. USB 2.0 High Speed (480Mbits/second) and Full Speed (12Mbits/second) compatible. Dual Multi-Protocol Synchronous Serial Engine (MPSSE) to simplify synchronous serial protocol (USB to JTAG, I2C, SPI or bit-bang) design. Dual independent UART or FIFO ports configurable using MPSSEs. Independent Baud rate generators. RS232/RS422/RS485 UART Transfer Data Rate up to 12Mbaud. (RS232 Data Rate limited by external level shifter). USB to parallel FIFO transfer data rate up to 10Mbyte/sec. Single channel synchronous FIFO mode for transfers up to 40 Mbytes/sec. CPU-style FIFO interface mode simplifies CPU interface design. MCU host bus emulation mode configuration option. Fast Opto-Isolated serial interface option. FTDI’s royalty-free Virtual Com Port (VCP) and Direct (D2XX) drivers eliminate the requirement for USB driver development in most cases. Adjustable receive buffer timeout. Option for transmit and receive LED drive signals on each channel. Enhanced bit-bang Mode interface option with RD# and WR# strobes. FT245B-style FIFO interface option with bidirectional data bus and simple 4 wire handshake interface. Highly integrated design includes +1.8V LDO regulator for VCORE, integrated POR function and on chip clock multiplier PLL (12MHz – 480MHz). Asynchronous serial UART interface option with full hardware handshaking and modem interface signals. Fully assisted hardware or X-On / X-Off software handshaking. UART Interface supports 7/8 bit data, 1/2 stop bits, and Odd/Even/Mark/Space/No Parity. Auto-transmit enable control for RS485 serial applications using TXDEN pin. Operational configuration mode and USB Description strings configurable in external EEPROM over the USB interface. Configurable I/O drive strength (4,8,12 or 16mA) and slew rate. Low operating and USB suspend current. Supports bus powered, self powered and high-power bus powered USB configurations. UHCI/OHCI/EHCI host controller compatible. USB Bulk data transfer mode (512 byte packets in Hi-Speed mode). +1.8V (chip core) and +3.3V I/O interfacing (+5V Tolerant). Extended -40°C to 85°C industrial operating temperature range. Compact 64-LD Lead Free LQFP/LQFN package and 56-LD VQFN packages. +3.3V single supply operating voltage range.
아무튼 jtag-hs2를 연결해서 리눅스에서 보면 그냥 시리얼 포트다 (연결되었다 끊어지지만)
$ lsusb -t -v |__ Port 2: Dev 3, If 0, Class=Vendor Specific Class, Driver=ftdi_sio, 480M ID 0403:6014 Future Technology Devices International, Ltd FT232H Single HS USB-UART/FIFO IC
$ sudo dmesg [ 924.904844] usb 1-2: new high-speed USB device number 14 using xhci_hcd [ 925.059009] usb 1-2: New USB device found, idVendor=0403, idProduct=6014, bcdDevice= 9.00 [ 925.059027] usb 1-2: New USB device strings: Mfr=1, Product=2, SerialNumber=3 [ 925.059034] usb 1-2: Product: Digilent USB Device [ 925.059040] usb 1-2: Manufacturer: Digilent [ 925.059045] usb 1-2: SerialNumber: 0000000000 [ 925.066084] ftdi_sio 1-2:1.0: FTDI USB Serial Device converter detected [ 925.066178] usb 1-2: Detected FT232H [ 925.067712] usb 1-2: FTDI USB Serial Device converter now attached to ttyUSB0 [ 925.104014] ftdi_sio ttyUSB0: FTDI USB Serial Device converter now disconnected from ttyUSB0 [ 925.104066] ftdi_sio 1-2:1.0: device disconnected