Arduino互換Metaboardを紐解く
安くArduinoが欲しい。そんな中でArduinoUNOとか高いし、安上がりでArduinoは手に入らないかと考えていたところ、Metaboardというマイコン一つでArduinoが作れるというのを知る。本来、ArduinoはコアとなるAVRマイコンとそのマイコンにファームウエアを書き込むためのUSB付きマイコンがセットになっているのだが、ここではV-USBベースのUSBaspをブートローダーとして機能し単体でUSBからファームウエアの書き換えが可能なArduinoを制作した。
スペックはATmega328pな20MHzであわよくば、ブートローダをブラッシュアップしようと思ったが逆にコードサイズが大きくなっただけという、どうしてこうなった。
main.c
#include <avr/io.h> #include <avr/interrupt.h> #include <avr/wdt.h> #include <avr/boot.h> #include <avr/eeprom.h> #include <util/delay.h> #include "usbdrv.c" /* ------------------------------------------------------------------------ */ /* Request constants used by USBasp */ #define USBASP_FUNC_CONNECT 1 #define USBASP_FUNC_DISCONNECT 2 #define USBASP_FUNC_TRANSMIT 3 #define USBASP_FUNC_READFLASH 4 #define USBASP_FUNC_ENABLEPROG 5 #define USBASP_FUNC_WRITEFLASH 6 #define USBASP_FUNC_READEEPROM 7 #define USBASP_FUNC_WRITEEEPROM 8 #define USBASP_FUNC_SETLONGADDRESS 9 #if (FLASHEND) > 0xffff /* we need long addressing */ #define CURRENT_ADDRESS currentAddress.l #define addr_t uint32_t #else #define CURRENT_ADDRESS currentAddress.w[0] #define addr_t uint16_t #endif typedef union longConverter{ addr_t l; uint16_t w[sizeof(addr_t)/2]; uchar b[sizeof(addr_t)]; } longConverter_t; static uchar requestBootLoaderExit; static longConverter_t currentAddress; /* in bytes */ static uchar bytesRemaining; static uchar isLastPage; static uchar currentRequest; static const uchar signatureBytes[4] = { #ifdef SIGNATURE_BYTES SIGNATURE_BYTES #elif defined (__AVR_ATmega168__) || defined (__AVR_ATmega168P__) 0x1e, 0x94, 0x06, 0 #elif defined (__AVR_ATmega328P__) 0x1e, 0x95, 0x0f, 0 #else #error "Device signature is not known, please edit main.c!" #endif }; /* ------------------------------------------------------------------------ */ uchar usbFunctionSetup(uchar data[8]) { static uchar replyBuffer[4]; usbRequest_t *rq = (void *)data; uchar len = 0; usbMsgPtr = replyBuffer; if(rq->bRequest == USBASP_FUNC_TRANSMIT){ /* emulate parts of ISP protocol */ { uchar rval = 0; usbWord_t address; address.bytes[1] = rq->wValue.bytes[1]; address.bytes[0] = rq->wIndex.bytes[0]; if(rq->wValue.bytes[0] == 0x30){ /* read signature */ rval = rq->wIndex.bytes[0] & 3; rval = signatureBytes[rval]; } else if(rq->wValue.bytes[0] == 0xa0){ /* read EEPROM byte */ rval = eeprom_read_byte((void *)address.word); } else if(rq->wValue.bytes[0] == 0xc0){ /* write EEPROM byte */ eeprom_write_byte((void *)address.word, rq->wIndex.bytes[1]); } else { /* ignore all others, return default value == 0 */ } replyBuffer[3] = rval; len = 4; } } else if(rq->bRequest == USBASP_FUNC_ENABLEPROG){ len = 1; } else if(rq->bRequest >= USBASP_FUNC_READFLASH && rq->bRequest <= USBASP_FUNC_SETLONGADDRESS){ currentAddress.w[0] = rq->wValue.word; if(rq->bRequest == USBASP_FUNC_SETLONGADDRESS){ #if (FLASHEND) > 0xffff currentAddress.w[1] = rq->wIndex.word; #endif } else { bytesRemaining = rq->wLength.bytes[0]; isLastPage = rq->wIndex.bytes[1] & 0x02; currentRequest = rq->bRequest; len = 0xff; /* hand over to usbFunctionRead() / usbFunctionWrite() */ } } else if(rq->bRequest == USBASP_FUNC_DISCONNECT){ requestBootLoaderExit = 1; /* allow proper shutdown/close of connection */ } else { /* ignore: USBASP_FUNC_CONNECT */ } return len; } uchar usbFunctionWrite(uchar *data, uchar len) { uchar isLast; if(len > bytesRemaining){ len = bytesRemaining; } bytesRemaining -= len; if(bytesRemaining == 0){ isLast = 1; } if(currentRequest >= USBASP_FUNC_READEEPROM){ { uchar i; for(i = 0; i < len; i++){ eeprom_write_byte((void *)(currentAddress.w[0]++), *data++); } } } else { { uchar i; for(i = 0; i < len;){ if((currentAddress.w[0] & (SPM_PAGESIZE - 1)) == 0){ /* if page start: erase */ cli(); boot_page_erase(CURRENT_ADDRESS); /* erase page */ sei(); boot_spm_busy_wait(); /* wait until page is erased */ } i += 2; cli(); boot_page_fill(CURRENT_ADDRESS, *(uint16_t *)data); sei(); CURRENT_ADDRESS += 2; data += 2; /* write page when we cross page boundary or we have the last partial page */ if((currentAddress.w[0] & (SPM_PAGESIZE - 1)) == 0 || (isLast && i >= len && isLastPage)){ cli(); boot_page_write(CURRENT_ADDRESS - 2); sei(); boot_spm_busy_wait(); cli(); boot_rww_enable(); sei(); } } } } return isLast; } uchar usbFunctionRead(uchar *data, uchar len) { if(len > bytesRemaining){ len = bytesRemaining; } bytesRemaining -= len; { uchar i; for(i = 0; i < len; i++){ if(currentRequest >= USBASP_FUNC_READEEPROM){ *data = eeprom_read_byte((void *)currentAddress.w[0]); } else { *data = pgm_read_byte((void *)CURRENT_ADDRESS); } data++; CURRENT_ADDRESS++; } } return len; } /* ------------------------------------------------------------------------ */ static void (*nullVector)(void) __attribute__((__noreturn__)); static void __attribute__((__noreturn__)) leaveBootloader() { cli(); USB_INTR_ENABLE = 0; USB_INTR_CFG = 0; /* also reset config bits */ MCUCR = (1 << IVCE); /* enable change of interrupt vectors */ MCUCR = (0 << IVSEL); /* move interrupts to application flash section */ /* We must go through a global function pointer variable instead of writing * ((void (*)(void))0)(); * because the compiler optimizes a constant 0 to "rcall 0" which is not * handled correctly by the assembler. */ nullVector(); } int __attribute__((noreturn)) main(void) { if(!(MCUSR & (1 << EXTRF))){ /* If this was not an external reset, ignore */ leaveBootloader(); } wdt_disable(); MCUSR = 0; /* clear all reset flags for next time */ MCUCR = (1 << IVCE); /* enable change of interrupt vectors */ MCUCR = (1 << IVSEL); /* move interrupts to boot flash section */ usbInit(); usbDeviceDisconnect(); { uchar i = 0; while(--i){ _delay_ms(1); } } usbDeviceConnect(); sei(); for(;;) { if(requestBootLoaderExit){ _delay_loop_2(65535); break; } usbPoll(); } usbDeviceDisconnect(); leaveBootloader(); }
usbconfig.h
/* Name: usbconfig.h * Project: V-USB, virtual USB port for Atmel's(r) AVR(r) microcontrollers * Author: Christian Starkjohann * Creation Date: 2005-04-01 * Tabsize: 4 * Copyright: (c) 2005 by OBJECTIVE DEVELOPMENT Software GmbH * License: GNU GPL v2 (see License.txt), GNU GPL v3 or proprietary (CommercialLicense.txt) * This Revision: $Id: usbconfig-prototype.h 785 2010-05-30 17:57:07Z cs $ */ #ifndef __usbconfig_h_included__ #define __usbconfig_h_included__ /* General Description: This file is an example configuration (with inline documentation) for the USB driver. It configures V-USB for USB D+ connected to Port D bit 2 (which is also hardware interrupt 0 on many devices) and USB D- to Port D bit 4. You may wire the lines to any other port, as long as D+ is also wired to INT0 (or any other hardware interrupt, as long as it is the highest level interrupt, see section at the end of this file). + To create your own usbconfig.h file, copy this file to your project's + firmware source directory) and rename it to "usbconfig.h". + Then edit it accordingly. */ /* ---------------------------- Hardware Config ---------------------------- */ #define USB_CFG_IOPORTNAME D /* This is the port where the USB bus is connected. When you configure it to * "B", the registers PORTB, PINB and DDRB will be used. */ #define USB_CFG_DMINUS_BIT 4 /* This is the bit number in USB_CFG_IOPORT where the USB D- line is connected. * This may be any bit in the port. */ #define USB_CFG_DPLUS_BIT 2 /* This is the bit number in USB_CFG_IOPORT where the USB D+ line is connected. * This may be any bit in the port. Please note that D+ must also be connected * to interrupt pin INT0! [You can also use other interrupts, see section * "Optional MCU Description" below, or you can connect D- to the interrupt, as * it is required if you use the USB_COUNT_SOF feature. If you use D- for the * interrupt, the USB interrupt will also be triggered at Start-Of-Frame * markers every millisecond.] */ #define USB_CFG_CLOCK_KHZ (F_CPU/1000) /* Clock rate of the AVR in kHz. Legal values are 12000, 12800, 15000, 16000, * 16500, 18000 and 20000. The 12.8 MHz and 16.5 MHz versions of the code * require no crystal, they tolerate +/- 1% deviation from the nominal * frequency. All other rates require a precision of 2000 ppm and thus a * crystal! * Since F_CPU should be defined to your actual clock rate anyway, you should * not need to modify this setting. */ #define USB_CFG_CHECK_CRC 0 /* Define this to 1 if you want that the driver checks integrity of incoming * data packets (CRC checks). CRC checks cost quite a bit of code size and are * currently only available for 18 MHz crystal clock. You must choose * USB_CFG_CLOCK_KHZ = 18000 if you enable this option. */ /* ----------------------- Optional Hardware Config ------------------------ */ /* #define USB_CFG_PULLUP_IOPORTNAME D */ /* If you connect the 1.5k pullup resistor from D- to a port pin instead of * V+, you can connect and disconnect the device from firmware by calling * the macros usbDeviceConnect() and usbDeviceDisconnect() (see usbdrv.h). * This constant defines the port on which the pullup resistor is connected. */ /* #define USB_CFG_PULLUP_BIT 4 */ /* This constant defines the bit number in USB_CFG_PULLUP_IOPORT (defined * above) where the 1.5k pullup resistor is connected. See description * above for details. */ /* --------------------------- Functional Range ---------------------------- */ #define USB_CFG_HAVE_INTRIN_ENDPOINT 0 /* Define this to 1 if you want to compile a version with two endpoints: The * default control endpoint 0 and an interrupt-in endpoint (any other endpoint * number). */ #define USB_CFG_HAVE_INTRIN_ENDPOINT3 0 /* Define this to 1 if you want to compile a version with three endpoints: The * default control endpoint 0, an interrupt-in endpoint 3 (or the number * configured below) and a catch-all default interrupt-in endpoint as above. * You must also define USB_CFG_HAVE_INTRIN_ENDPOINT to 1 for this feature. */ #define USB_CFG_EP3_NUMBER 3 /* If the so-called endpoint 3 is used, it can now be configured to any other * endpoint number (except 0) with this macro. Default if undefined is 3. */ /* #define USB_INITIAL_DATATOKEN USBPID_DATA1 */ /* The above macro defines the startup condition for data toggling on the * interrupt/bulk endpoints 1 and 3. Defaults to USBPID_DATA1. * Since the token is toggled BEFORE sending any data, the first packet is * sent with the oposite value of this configuration! */ #define USB_CFG_IMPLEMENT_HALT 0 /* Define this to 1 if you also want to implement the ENDPOINT_HALT feature * for endpoint 1 (interrupt endpoint). Although you may not need this feature, * it is required by the standard. We have made it a config option because it * bloats the code considerably. */ #define USB_CFG_SUPPRESS_INTR_CODE 0 /* Define this to 1 if you want to declare interrupt-in endpoints, but don't * want to send any data over them. If this macro is defined to 1, functions * usbSetInterrupt() and usbSetInterrupt3() are omitted. This is useful if * you need the interrupt-in endpoints in order to comply to an interface * (e.g. HID), but never want to send any data. This option saves a couple * of bytes in flash memory and the transmit buffers in RAM. */ #define USB_CFG_INTR_POLL_INTERVAL 10 /* If you compile a version with endpoint 1 (interrupt-in), this is the poll * interval. The value is in milliseconds and must not be less than 10 ms for * low speed devices. */ #define USB_CFG_IS_SELF_POWERED 0 /* Define this to 1 if the device has its own power supply. Set it to 0 if the * device is powered from the USB bus. */ #define USB_CFG_MAX_BUS_POWER 100 /* Set this variable to the maximum USB bus power consumption of your device. * The value is in milliamperes. [It will be divided by two since USB * communicates power requirements in units of 2 mA.] */ #define USB_CFG_IMPLEMENT_FN_WRITE 1 /* Set this to 1 if you want usbFunctionWrite() to be called for control-out * transfers. Set it to 0 if you don't need it and want to save a couple of * bytes. */ #define USB_CFG_IMPLEMENT_FN_READ 1 /* Set this to 1 if you need to send control replies which are generated * "on the fly" when usbFunctionRead() is called. If you only want to send * data from a static buffer, set it to 0 and return the data from * usbFunctionSetup(). This saves a couple of bytes. */ #define USB_CFG_IMPLEMENT_FN_WRITEOUT 0 /* Define this to 1 if you want to use interrupt-out (or bulk out) endpoints. * You must implement the function usbFunctionWriteOut() which receives all * interrupt/bulk data sent to any endpoint other than 0. The endpoint number * can be found in 'usbRxToken'. */ #define USB_CFG_HAVE_FLOWCONTROL 0 /* Define this to 1 if you want flowcontrol over USB data. See the definition * of the macros usbDisableAllRequests() and usbEnableAllRequests() in * usbdrv.h. */ #define USB_CFG_DRIVER_FLASH_PAGE 0 /* If the device has more than 64 kBytes of flash, define this to the 64 k page * where the driver's constants (descriptors) are located. Or in other words: * Define this to 1 for boot loaders on the ATMega128. */ #define USB_CFG_LONG_TRANSFERS 0 /* Define this to 1 if you want to send/receive blocks of more than 254 bytes * in a single control-in or control-out transfer. Note that the capability * for long transfers increases the driver size. */ /* #define USB_RX_USER_HOOK(data, len) if(usbRxToken == (uchar)USBPID_SETUP) blinkLED(); */ /* This macro is a hook if you want to do unconventional things. If it is * defined, it's inserted at the beginning of received message processing. * If you eat the received message and don't want default processing to * proceed, do a return after doing your things. One possible application * (besides debugging) is to flash a status LED on each packet. */ /* #define USB_RESET_HOOK(resetStarts) if(!resetStarts){hadUsbReset();} */ /* This macro is a hook if you need to know when an USB RESET occurs. It has * one parameter which distinguishes between the start of RESET state and its * end. */ /* #define USB_SET_ADDRESS_HOOK() hadAddressAssigned(); */ /* This macro (if defined) is executed when a USB SET_ADDRESS request was * received. */ #define USB_COUNT_SOF 0 /* define this macro to 1 if you need the global variable "usbSofCount" which * counts SOF packets. This feature requires that the hardware interrupt is * connected to D- instead of D+. */ /* #ifdef __ASSEMBLER__ * macro myAssemblerMacro * in YL, TCNT0 * sts timer0Snapshot, YL * endm * #endif * #define USB_SOF_HOOK myAssemblerMacro * This macro (if defined) is executed in the assembler module when a * Start Of Frame condition is detected. It is recommended to define it to * the name of an assembler macro which is defined here as well so that more * than one assembler instruction can be used. The macro may use the register * YL and modify SREG. If it lasts longer than a couple of cycles, USB messages * immediately after an SOF pulse may be lost and must be retried by the host. * What can you do with this hook? Since the SOF signal occurs exactly every * 1 ms (unless the host is in sleep mode), you can use it to tune OSCCAL in * designs running on the internal RC oscillator. * Please note that Start Of Frame detection works only if D- is wired to the * interrupt, not D+. THIS IS DIFFERENT THAN MOST EXAMPLES! */ #define USB_CFG_CHECK_DATA_TOGGLING 0 /* define this macro to 1 if you want to filter out duplicate data packets * sent by the host. Duplicates occur only as a consequence of communication * errors, when the host does not receive an ACK. Please note that you need to * implement the filtering yourself in usbFunctionWriteOut() and * usbFunctionWrite(). Use the global usbCurrentDataToken and a static variable * for each control- and out-endpoint to check for duplicate packets. */ #define USB_CFG_HAVE_MEASURE_FRAME_LENGTH 0 /* define this macro to 1 if you want the function usbMeasureFrameLength() * compiled in. This function can be used to calibrate the AVR's RC oscillator. */ #define USB_USE_FAST_CRC 0 /* The assembler module has two implementations for the CRC algorithm. One is * faster, the other is smaller. This CRC routine is only used for transmitted * messages where timing is not critical. The faster routine needs 31 cycles * per byte while the smaller one needs 61 to 69 cycles. The faster routine * may be worth the 32 bytes bigger code size if you transmit lots of data and * run the AVR close to its limit. */ /* -------------------------- Device Description --------------------------- */ #define USB_CFG_VENDOR_ID 0xc0, 0x16 /* = 0x16c0 = 5824 = voti.nl */ /* USB vendor ID for the device, low byte first. If you have registered your * own Vendor ID, define it here. Otherwise you may use one of obdev's free * shared VID/PID pairs. Be sure to read USB-IDs-for-free.txt for rules! * *** IMPORTANT NOTE *** * This template uses obdev's shared VID/PID pair for Vendor Class devices * with libusb: 0x16c0/0x5dc. Use this VID/PID pair ONLY if you understand * the implications! */ #define USB_CFG_DEVICE_ID 0xdc, 0x05 /* = 0x05dc = 1500 */ /* This is the ID of the product, low byte first. It is interpreted in the * scope of the vendor ID. If you have registered your own VID with usb.org * or if you have licensed a PID from somebody else, define it here. Otherwise * you may use one of obdev's free shared VID/PID pairs. See the file * USB-IDs-for-free.txt for details! * *** IMPORTANT NOTE *** * This template uses obdev's shared VID/PID pair for Vendor Class devices * with libusb: 0x16c0/0x5dc. Use this VID/PID pair ONLY if you understand * the implications! */ #define USB_CFG_DEVICE_VERSION 0x02, 0x01 /* Version number of the device: Minor number first, then major number. */ #define USB_CFG_VENDOR_NAME 'w','w','w','.','f','i','s','c','h','l','.','d','e' #define USB_CFG_VENDOR_NAME_LEN 13 /* These two values define the vendor name returned by the USB device. The name * must be given as a list of characters under single quotes. The characters * are interpreted as Unicode (UTF-16) entities. * If you don't want a vendor name string, undefine these macros. * ALWAYS define a vendor name containing your Internet domain name if you use * obdev's free shared VID/PID pair. See the file USB-IDs-for-free.txt for * details. */ #define USB_CFG_DEVICE_NAME 'U', 'S', 'B', 'a', 's', 'p' #define USB_CFG_DEVICE_NAME_LEN 6 /* Same as above for the device name. If you don't want a device name, undefine * the macros. See the file USB-IDs-for-free.txt before you assign a name if * you use a shared VID/PID. */ /*#define USB_CFG_SERIAL_NUMBER 'N', 'o', 'n', 'e' */ /*#define USB_CFG_SERIAL_NUMBER_LEN 0 */ /* Same as above for the serial number. If you don't want a serial number, * undefine the macros. * It may be useful to provide the serial number through other means than at * compile time. See the section about descriptor properties below for how * to fine tune control over USB descriptors such as the string descriptor * for the serial number. */ #define USB_CFG_DEVICE_CLASS 0 /* set to 0 if deferred to interface */ #define USB_CFG_DEVICE_SUBCLASS 0 /* See USB specification if you want to conform to an existing device class. * Class 0xff is "vendor specific". */ #define USB_CFG_INTERFACE_CLASS 0 /* define class here if not at device level */ #define USB_CFG_INTERFACE_SUBCLASS 0 #define USB_CFG_INTERFACE_PROTOCOL 0 /* See USB specification if you want to conform to an existing device class or * protocol. The following classes must be set at interface level: * HID class is 3, no subclass and protocol required (but may be useful!) * CDC class is 2, use subclass 2 and protocol 1 for ACM */ /* #define USB_CFG_HID_REPORT_DESCRIPTOR_LENGTH 42 */ /* Define this to the length of the HID report descriptor, if you implement * an HID device. Otherwise don't define it or define it to 0. * If you use this define, you must add a PROGMEM character array named * "usbHidReportDescriptor" to your code which contains the report descriptor. * Don't forget to keep the array and this define in sync! */ /* #define USB_PUBLIC static */ /* Use the define above if you #include usbdrv.c instead of linking against it. * This technique saves a couple of bytes in flash memory. */ /* ------------------- Fine Control over USB Descriptors ------------------- */ /* If you don't want to use the driver's default USB descriptors, you can * provide our own. These can be provided as (1) fixed length static data in * flash memory, (2) fixed length static data in RAM or (3) dynamically at * runtime in the function usbFunctionDescriptor(). See usbdrv.h for more * information about this function. * Descriptor handling is configured through the descriptor's properties. If * no properties are defined or if they are 0, the default descriptor is used. * Possible properties are: * + USB_PROP_IS_DYNAMIC: The data for the descriptor should be fetched * at runtime via usbFunctionDescriptor(). If the usbMsgPtr mechanism is * used, the data is in FLASH by default. Add property USB_PROP_IS_RAM if * you want RAM pointers. * + USB_PROP_IS_RAM: The data returned by usbFunctionDescriptor() or found * in static memory is in RAM, not in flash memory. * + USB_PROP_LENGTH(len): If the data is in static memory (RAM or flash), * the driver must know the descriptor's length. The descriptor itself is * found at the address of a well known identifier (see below). * List of static descriptor names (must be declared PROGMEM if in flash): * char usbDescriptorDevice[]; * char usbDescriptorConfiguration[]; * char usbDescriptorHidReport[]; * char usbDescriptorString0[]; * int usbDescriptorStringVendor[]; * int usbDescriptorStringDevice[]; * int usbDescriptorStringSerialNumber[]; * Other descriptors can't be provided statically, they must be provided * dynamically at runtime. * * Descriptor properties are or-ed or added together, e.g.: * #define USB_CFG_DESCR_PROPS_DEVICE (USB_PROP_IS_RAM | USB_PROP_LENGTH(18)) * * The following descriptors are defined: * USB_CFG_DESCR_PROPS_DEVICE * USB_CFG_DESCR_PROPS_CONFIGURATION * USB_CFG_DESCR_PROPS_STRINGS * USB_CFG_DESCR_PROPS_STRING_0 * USB_CFG_DESCR_PROPS_STRING_VENDOR * USB_CFG_DESCR_PROPS_STRING_PRODUCT * USB_CFG_DESCR_PROPS_STRING_SERIAL_NUMBER * USB_CFG_DESCR_PROPS_HID * USB_CFG_DESCR_PROPS_HID_REPORT * USB_CFG_DESCR_PROPS_UNKNOWN (for all descriptors not handled by the driver) * * Note about string descriptors: String descriptors are not just strings, they * are Unicode strings prefixed with a 2 byte header. Example: * int serialNumberDescriptor[] = { * USB_STRING_DESCRIPTOR_HEADER(6), * 'S', 'e', 'r', 'i', 'a', 'l' * }; */ #define USB_CFG_DESCR_PROPS_DEVICE 0 #define USB_CFG_DESCR_PROPS_CONFIGURATION 0 #define USB_CFG_DESCR_PROPS_STRINGS 0 #define USB_CFG_DESCR_PROPS_STRING_0 0 #define USB_CFG_DESCR_PROPS_STRING_VENDOR 0 #define USB_CFG_DESCR_PROPS_STRING_PRODUCT 0 #define USB_CFG_DESCR_PROPS_STRING_SERIAL_NUMBER 0 #define USB_CFG_DESCR_PROPS_HID 0 #define USB_CFG_DESCR_PROPS_HID_REPORT 0 #define USB_CFG_DESCR_PROPS_UNKNOWN 0 /* ----------------------- Optional MCU Description ------------------------ */ /* The following configurations have working defaults in usbdrv.h. You * usually don't need to set them explicitly. Only if you want to run * the driver on a device which is not yet supported or with a compiler * which is not fully supported (such as IAR C) or if you use a differnt * interrupt than INT0, you may have to define some of these. */ /* #define USB_INTR_CFG MCUCR */ /* #define USB_INTR_CFG_SET ((1 << ISC00) | (1 << ISC01)) */ /* #define USB_INTR_CFG_CLR 0 */ /* #define USB_INTR_ENABLE GIMSK */ /* #define USB_INTR_ENABLE_BIT INT0 */ /* #define USB_INTR_PENDING GIFR */ /* #define USB_INTR_PENDING_BIT INTF0 */ /* #define USB_INTR_VECTOR INT0_vect */ #endif /* __usbconfig_h_included__ */
回路図
信号線とマイコンのポート接続に68Ωが使われているが、ちょっと低すぎ?V-USBじゃなくAVRUSBの名称だった時代は75Ωだった気がするのだが…。D-プルアップ用の抵抗も2.2kΩから1.5kΩに変更されている。あと、耐圧3.6Vのダイオードが使われているが、オシロでみると絶対定格の4Vを適切にクリップせずにオーバーしてしまうケースがみられる。3Vでもいいかもしれない。
AVR側のポートの閾値が5V動作の時2.5Vなのでそれを下回らない程度で十分で直流で3.3Vを超えるとUSB側の保護機能が働き動作しない場合がある。とくにダイオードを省いた構成のMetaboardをみかけるが、USBポートを痛めたくなければダイオードは必須であると思われる。
また上記のファームウエアにおいてはブートローダーを無効化設定するジャンパピンの構成を省いてある。
ソフトウエア
USBasp - USB programmer for Atmel AVR controllers - fischl.de
以上からドライバがダウンロードできます。hidaspxはAvrdudeなどの海外製書き込みソフトが対応してないですが、USBaspは対応しているので(プロジェクト的な)メンテナンスや対応ハードウエアの面で安心です。
Arduino Sketchの設定
Processing/スケッチのディレクトリ/フォルダにある。hardware/boards.txtに下記を加えます。
############################################################## metaboard.name=Metaboard metaboard.upload.protocol=usbasp metaboard.upload.maximum_size=14336 metaboard.upload.speed=19200 metaboard.build.mcu=atmega328p metaboard.build.f_cpu=20000000L metaboard.build.core=arduino metaboard.upload.disable_flushing=true ##############################################################