Projects Internet Elektor Internet Radio (EIR) - Egnite
projectsinternet radioElektor Internet RadiListening to radio programmes with theHarald Kipp and Dr Thomas SchererIn the good old days, you had to modulate audio signals onto an RF carrier so they could be receivedand demodulated to produce something more or less audible. Nowadays things are different: audiosignals are compressed and put into IP packets that are ‘streamed’, and you can access every Internetradio programme in the world by receiving, buffering and decompressing these packages. This is allvery easy with the state-of-the-art hardware described in this article.Internet radio is something quite special: even the most sensitive shortwave receiver cannot come close toproviding such a broad range of programmes, and the sound quality issimply not comparable. As the ‘Internet broadcasters’ that provide theseprogrammes do not have to pump several hundred kilowatts of RF energyin the air (with the resulting ‘electrosmog’), this type of broadcasting operation is also quite economical for relatively small target audiences.We could say a lot more about the advantages of this new sort of radio (seeinset), but what’s more important is toanswer the question posed in the nextsection.Why not use a pure software solution?First of all, we have to say that there are several programs (WinAmp,iTunes, VLC, etc.) that are availableentirely free of charge for all possibleoperating systems and can be usedto listen to Internet radio. Every true21st-century person has a PC, Mac orLinux machine available somewhere,so why should you spend money on anon-virtual, physical device, and on topof that build it yourself?Well, for one thing the hardware platform for a software radio consumeselectricity, and quite a lot for this purpose. Anyone who spends a good dealof time listening to radio programmeswith a PC is engaged in a very environmentally unfriendly activity. The solu-16tion proposed here manages to do thejob with a power consumption of only1 watt. If you use it 10 hours a day, thesavings in electricity costs alone (relative to using a gamer PC as a radio) areenough to repay you investment withinsix months.For another thing, there are applications for which a PC is not such a clever solution, such as connection to astereo system. A DIY Internet radio based on Open Source technology is easyto extend and adapt to special requirements – and last but not least, the EIRkeeps on working when your PC hangsor crashes .Operating principleAs the EIR is a complex project thatuses state-of-the-art hardware, it isimpossible to deal adequately with allrelevant topics in a single article. Forthis reason, the main objective of thisarticle is to describe the hardware andtell you how to assemble it and put itinto service. You can find additional information in documents on the Elektorwebsite (www.elektor.com) and theproject website [1], and there will beadditional articles on this subject in future issues.As you probably already realise, an Internet radio must receive, buffer anddecode data streams. This means thatone of its basic ingredients must be areasonable microcontroller. As alreadymentioned in the last issue of Elektor[3], an ARM7 MCU [4] can provide thenecessary processing power.The basic architecture is shown in Figure 1. The MCU is shown in the upper middle of the diagram, and it hasaccess to a healthy 64 MB of SDRAM– which is sufficient for the buffer andquite a few ‘extras’. The MCU has roomfor the firmware, and there is also 4 MBof flash memory available for non-volatile data storage. A real-time clock backed up by a Supercap allows the circuit to be used to implement an alarmradio or other applications that dependon knowing the current time. To avoid having to exploit the full capacityof the ARM7 MCU, audio decoding ishandled by a VS1053 IC [5], which isspecifically designed for this purpose.The EIR also provides a comfortableselection of interfaces: beside the mandatory Ethernet port (since the EIR hasto access the Internet somehow), there is a USB programming interface fordownloading new firmware, a serialport and a JTAG port (useful for debugging), and three useful expansionconnectors at the port level.To allow you to record broadcasts ifyou so desire, there is also a slot for anMMC/SD memory card.General aspectsThe incoming data streams are normally compressed to such an extent thatthey can handle sampled stereo data,which typically has a resolution ofelektor - 4/2008
dio (EIR)latest ICs16 bits and a sampling rate of 44.1 kHz,using a data transmission rate as lowas 192 kbit/s (or even less) instead ofthe normal rate of around 1.4 Mbit/s.This means that a buffer with a capacity of approximately 10 seconds canbe implemented with around 256 KBof RAM. This may not sound like muchnowadays, but it is still quite a heftychunk of memory for a microcontroller.If you want to be on the safe side andalso want to have room for Internet niceties and other ‘extras’, you can quickly end up with 512 kB or more. TheARM7 MCU selected for this designsupports SDRAM, so the EIR with its64 MB of RAM does not suffer from anyshortage of memory.We chose Nut/OS as the operatingsystem. It is quite accommodating incomparison with Linux and can manage with less than 40 kB of memory.All in all, the software needs around200 kB of memory. A capacity of 1 MBis ample for data storage. As the MCUalready has 512 kB of flash memory onboard for program data as well as anabundance of RAM, there are no bottlenecks. All of the software is OpenSource, except for the flash programming software from Atmel.devise upgradesthatsupport this capability and other conceivable features.4/2008 - elektorAs you can see immediately from looking at the schematic diagram in Figure 2, this is a complex design. Forthis reason, the following descriptionis based on the functional blocks.In order to avoid constraining the formof any possible extensions, no user interface components (such as buttonsor a display) are incorporated in theboard. However, they can easily beconnected via the expansion connectors. The EIR is intended to form thebasis for user-designed expansions,and the firmware that comes with theboard is thus designed to be used viaan integrated website. However, thefirmware is completely open, so otheroptions are always possible.5-24VPower SupplyVS1053Audio CodecAT91SAM7SE512ResetButtonMMC /SD-Card EthernetAccess to the Internet is via an Ethernet connector with an integrated transformer and two LEDs. The green LEDlights up when data is being transferred, while the yellow LED indicatesthat a connection is present. The Ethernet traffic is handled by a specialised IC (IC10, a DM9000E). Buffer IC9DM9000EEthernetWeb InterfaceUSBDevice / Prog.RS23264 MByteSDRAMExpansionConnectorOLEDTouch Wheel(later Upgrade)4 MByteDataFlashRTC / SuperCapIncidentally, the microcontroller hassufficient processing power to allowa second audio stream to be recordedon the SD card while another stream isplaying. It will certainly not take verylong for the Open Source community toDetailsJTAGConnectorFigure 1. Block diagram of the Elektor Internet Radio.17
24PB26PB28PB30S1 3V34321R46Port B17191820JTAG15 NRST16(optional)13 TDO140Ω2175PB23 TIOA0/A0/NBS0IC327 ΩR227 ΩR1596061PB8PB7PB66267PB2PB568BZA408856R105 not mounted11 2GNDD D–VBUS39373533911PB8 3V3USB C1R310nC822p22pRESETS1R6 3V3X1 A10PA6PA7Short 1 - 3 and2 - 4 for 1081071310RXDJPPA8Short 3 - 5 and4 - 6 for C2 33312927252321191715131197531V 100nC2AD6AD4T1INC1–C1 00nC9522 ΩR48C40ΩR10222 ΩR48DR48B222 Ω3R48A122 A11PA9PA7PA5PA3PA1BLM31AL3 3V3Port AK15768K3Port 26242220181614121086424x 220pSHIELD-RC11 C12 C13 C14CTSTXDRTSRXD0Ω594837261Short K3 pins 34 and 36to erase C3PC1RS232G2G1PA[0.31]SDCKVINSHDN071081 - 11A 3V3K5ERASEShort K3 pins 33 and 35for boundary scan testJTAGSEL .23]PB[0.31]projectsinternet radio2aFigure 2. As you can see immediately from the schematic diagram of the EIR, this is a sophisticated project.elektor - 4/2008
4SD13SD14SD15TX ENCRSIOWAITRXI-TXD3TEST2TEST3TEST4TEST5LINK ORX CLKTX CLK124PA11CSSCKSISO7IC56RSTWP EUPEECSEECKEEDIAENRSTEEDOSDLINK XI TXD2GPIO0TXO-TXD1RXD0TXO SPEEDDUPLINKACTTXD0RX ERRX 4 MByteSerial PA20IC9 NC7WZ07P6X2IC95 3V346PC22IC9.AR2310kIC9.BPB20PB2 3V3 0nC360F33 27R34 R33 R3211yellow 12ActivityIC11PCF8563TOSC1D1 3V3K10greenR104RX-RX RCTNCNCTCTTX-TX 01%1%R25 3V310/100 Mbit EthernetC31R29Super CapR31 2PC1PC050 Ω50 ΩSD16k850 Ω50 ΩSD01k0ΩR3510kIOW100kPW 54244454748505153RCAP12.288MHzX222pC20(VS1053 may be replaced by VS1033)MP3 I2S SDATAGP106/I2S SCLKGP105/I2S MCLKGP104/I2S PC25PA28PC1418PC021764MByte µC26R9R1010nC27 A100kPC21100k10kR50B10kR50D5R14410k100n10µR15470 ΩR19470 ΩR2110nC22R1610 ΩR1110 ΩR12C16C1547nC23071081 - 11B10nC2122 ΩPC17100k22 Ω47nC291µC241µC2516V5433BZA4088564BZA4088 3V316V6 ASHIELD-C0ΩR103SHIELDSHIELDAudio OutK842135Audio InK9Do not mount R100before removing R18!42135R18MMC/SD-Card Socket 3V3CMNCCDCDPC18PC[0.23]100k10 ΩWPWPPC194/2008 - elektor0ΩPB[0.31]2b19
projectsinternet radio2cSHDNVINPMEG3005AEA 3V3310kSHDN500mA FLT16165V .24V DCGNDD4L1123D51%C391µ 1µ 100n25V 25V2SM6T24CAL2VINR4110µ1%PMEG3005AEADLW5BTN102SQ2 3V3 VREF 3V3VOUT5R39IC13LTC1844ES5310µC40 C41 C42410nR38-SDSHDN21 3710kK12D3C37200k4PMEG3005AEA1IC1210kBOOSTR36VX180 ΩFBVINF116k55D210µ1%KP-1608URCReplace R39 and R42 with 100k 1%for VS1033 (VX 2V5)VX 3V3 CORE128VDDPLLVDDFLASH5R431722 Ω24213146671149519120381234345GNDGNDC53 C54 C55 C56 C57 C58 C59124GNDGNDGNDGND941197010µ210µC5245C46 C47 C48 C49 C50 C5122C45GNDAT91SAM7SE512-AUC6010µ6x 100nC61277372553620590C7810µC79 C80 C81 C82 C83 C84 C8510µ3x 100n4x LR440Ω3x 100n 3V3A 3V3IC43125199148127766335894243234915C86C87 C88 C89C90C91 C92 C93 C947x 100n Audio decoderAlthough the ARM7 would just be ableto handle decoding of MP3 or AAC datain software, a dedicated IC such as IC7considerably reduces the load on theMCU, and it is specifically designed tohandle HE-AAC and even Ogg-Vorbisdata in addition to the usual MP3 versions. Logically enough, this also simplifies the application software. We useda pre-production sample from VLSI inthe prototypes. If you have trouble obtaining this IC, you can use the VS1033version (without Ogg Vorbis capability)instead. Although the MCU has a 1.8-Voutput for powering peripheral devices, a separate 1.8-V voltage regulatoris provided for IC7 for reasons of stability. If you use the VS1033, R39 and R42must be changed to 100 kΩ because itneeds a 2.5-V supply VDDQVSSQ2841546124652MT48LC128M16A2POWER10µallows the Wait input of the MCU to beused by expansion circuitry.20C71 C72 C7310µPOWER10µC70CVDD24IC1028C75 C76 C77C67 C68 C69DGND13x 100n 3V335C74C66DGND0CVDD1POWER10µ7x 100n 3V3C62 C63 C64 C65CVDD010µ3x 100n Supplementary flash memoryIt is necessary to store a large numberof operational settings for the radio,and they must remain available evenafter a power outage (especially thestation list). The internal flash memory of the MCU could be used for thispurpose, but writing data to it is cumbersome. To simplify the process, a serial flash memory (IC5) is included inthe design. With a capacity of 4 MB, ithas room for extensive station lists andeven more. Power supplyTo keep the power consumption of theEIR as low as possible, it is poweredby a switch-mode supply built aroundIC12. It provides around 5 watts ofpower at 3.3 V with an input voltage in the range of 5–24 V. As the EIRtakes only 1 W for its own use, thereis enough left over for DIY hardwareextensions.071081 - 11C4x 100n SolderingThe EIR is built on a densely populated multilayer PCB with lots of tinySMD components (see Figures 3 and4), with some of the IC pins spacedonly 0.5 mm apart. To avoid problemswith DIY assembly, Elektor can supplya pre-assembled board with all SMDsalready fitted (with the VS1053). Allyou have to do is to fit the relativelylarge components, which helps youavoid pernicious assembly errors. Forthe diehards, it is of course possible tobuild the board yourself using the layout artwork.Functional testFor initial testing of the power supply,the load on the 3.3-V side should be atleast several millampères (do not useit with no load). The voltage regulator should start working with at inputvoltage of at least 4 V and draw 50 toelektor - 4/2008
150 mA, depending on the load. Thiswill drop to 30–50 mA at 24 V. If everything is OK, LED1 will light up. Afterthe ICs are fitted, you can use an oscilloscope to check that the crystal isworking. If X1 is oscillating, the MCUshould be ready for action.The MCU comes with an on-boardboot loader that supports communication from and to the RAM and with theflash memory as well as downloadingnew firmware. The AT91-ISP.exe fileavailable from Atmel (see reference [6])installs the program SAM-BA, whichruns under Windows. After installingthis program, connect the EIR to yourPC via the USB port. After the poweris switched on, Windows should select the appropriate driver automatically. Now you can start SAM-BA. Select‘USB’ as the connection type and ‘AT91SAM7SE512-EK’ as the device (thisis largely compatible with the EIR).You can download a simple testingfirmware program from the Elektorwebsite. With this firmware and an operational MCU and serial interface, youcan check the other components, suchas the Ethernet port and the audio decoder. After downloading the firmwareto the MCU, you have to tell the EIRCOMPONENT LISTResistorsR1,R2 27Ω, SMD 0402R3 1kΩ5, SMD 0402R4,R5,R28,R45 1kΩ, SMD 0402R6,R23,R32,R33,R36,R38 10kΩ, SMD0402R7,R8,R18,R35,R44 0Ω, SMD 0402R9,R10,R13,R20,R22,R34 100kΩ, SMD0402R11,R12,R16 10Ω, SMD 0603R14,R15,R43 22Ω, SMD 0402R17 1MΩ, SMD 0402R19,R21 470Ω, SMD 0402R24,R25,R29,R30 50Ω 1%, SMD 0402R26,R27 1kΩ, SMD 1206R31 6kΩ8 1%, SMD 0603R37 16kΩ5 1%, SMD 0603R39 200kΩ* 1%, SMD 0402R40 180Ω, SMD 1206R41 10kΩ 1%, SMD 0402R42 470kΩ* 1%, SMD 0402R46 15kΩ, SMD 0402R47 22kΩ, SMD 0402R48 22Ω, array, CAY16R49 100kΩ, array, CAY16R50 10kΩ, array, CAY16R100-R106 0Ω*, SMD 1206 (notrequired)* see textCapacitors(SMD ceramic 6.3V unless otherwiseindicatedC1-C4,C16,C19,C30,C31,C35,C42, C46-4/2008 - elektorFigure 3. The component layout of the EIR. To avoid assembly problems, a board with prefitted SMD components is C73, C75,C76,C77,C79C85,C87,C88,C89,C91-C97 100nF,SMD 0402C5,C6,C9,C10,C17,C20,C32,C33,C34 22pF, SMD 0402C7,C38 1nF, SMD 0402C8,C21,C22,C27,C28,C37,C100 10nF,SMD 0402C11-C14 220pF, SMD 6,C90 10μF, SMD 0805C18,C23,C29 47nF, SMD 0402C24,C25,C26,C43 1μF, SMD 0805C36 0.1F, Double Layer CapFG0H104Z135C40,C41 1μF 25V, SMD 1206C98,C99 100μF 16V tantalum, SMDInductorsL1 DLW5BTN102SQ2 (Murata)L2 10μH, MSS5131 (Coilcraft)L3 BLM31A (Murata)SemiconductorsD1,D2,D3,D5 PMEG3005AEA (Philips)D4 SM6T24CA (STM)IC1 AT91SAM7SE512-AU (Atmel)IC2 MAX3222ECWN (Maxim)IC3, IC6, IC8 BZA408B diode arrayIC4 MT48LC32M16A2IC5 AT45DB321D-SU (Atmel)IC7 VS1053C-L (VLSI)*IC9 NC7WZ07P6X (Fairchild)IC10 DM9000E (Davicom)IC11 PCF8563T (Philips)IC12 LT1616 (Linear Technology)IC13 LTC1844ES5-SD (Linear Technology)LED1 KP-1608URC, red, SMD 0603(Kingbright)MiscellaneousX1 18.432 MHz quartz crystal, SMDHC49SMX2 12.288 MHz quartz crystal, SMDHC49SMX3 25.000 MHz quartz crystal, SMDHC49SMX4 32.678 kHz quartz crystal, SMDMC-146F1 fuse, 0.5A, fast, with holder, SMDOMNI-BLOK (Littelfuse)K1,K2,K3 40-way SIL pinheader, leadpitch 2.54mmK4 USB-B socket, AMP-787780K5 9-way sub-D plug, angled pins, USstandardK6 20-way boxheader, 2.54mm leadpitchK7 SD-card socket, SMD, FPS009-2700(Yamaichi)K8,K9 3.5-mm stereo jack socket, SMD,SJ1-3515 (CUI)K10 RJ-45 socket with Ethernet transformer and LEDs, SMD, RJLD-043TC (Taimag)K12 DC adaptor socket with 2-mm pin,TDC-002-3JP1 6-way 2-row pinheader with 2 jumpers, 2.54mm lead pitchS1 pushbutton, SMD, LSH (Schurter)PCB with pre-mounted SMD parts, ElektorShop # 071081-1Project software, archive 071081-11.zip;free downloads from www.elektor.com21
projectsinternet radioFigure 5. Screen shot of SAM-BA running under Windows 2000.leads swapped), and you can use a terminal emulator to send commands tothe EIR (we recommend TeraTerm [7]for Windows or Miniterm for Linux, andMacs have a built-in terminal utility).Listening to the radioFigure 4. As you can see from the fully assembled prototype, DIY soldering isn’t so easy here.that it should boot from this firmwarewhen it restarts. To do so, select theroutine ‘Boot from Flash (GPNVM2)’under ‘Scripts’ and click A22PA24PA26PA28PA30VrefAD4AD6GNDThen close SAM-BA and press the Reset button. Now the EIR can communicate with the PC via the serial interface and a null-modem cable (pin 2 & 3Table 1. Expansion connector K1UsePinSignal UseFree2PA1FreeFree4PA3TWI SDATWI SCL6PA5UART0 RxD via JP1UART0 TxD via JP18PA7UART0 RTSUART0 CTS10PA9DBUG RxD via JP1DBUG TxD via JP112PA11 Data Flash Chip SelectSPI MISO14PA13 SPI MOSISPI SPCK16PA15 MMC Chip SelectMMC Clock18PA17 MMC CommandMMC DAT020PA19 MMC DAT1 via R7MMC DAT2 via R822PA21 FreeFree24PA23 SDRAM DQMHSDRAM A1026PA25 SDRAM CKESDRAM Chip Select28PA27 SDRAM WESDRAM CAS30PA29 SDRAM RASIRQ1, MP3 Interrupt32PA31 MP3 Command SelectADC Reference343.3VPowerAnalogue input (free)36AD5Analogue input (free)Analogue input (free)38AD7Analogue input (free)Ground40GND GroundBefore you can start listening to theradio, you have to delete the testfirmware from the EIR and install theradio firmware. To allow new firmwareto be loaded, first connect pins 34 and36 of connector K3 with a jumper, thenpress Reset, and finally remove thejumper. After this, the EIR will startup again with the boot loader, and youcan use SAM-BA to download the radio firmware.Now connect the EIR to your local network via the Ethernet port (using a hub,a switch, or an Internet router with several ports) and connect the audio output to a headphone or an amplifier.If the LAN or the router you are usinghas an active DHCP server, the EIR willfetch a valid address and start playingthe programme from the default station. If you prefer to use fixed IP addresses, proceed as follows. When youinstall Nut/OS, a small utility called‘Discover’ is installed on the PC, andyou can always use it to find the EIR(see Figure 6) and then configure thedesired IP address. Enter the router address under ‘Gateway’, as illustratedin Figure 7. After this, you should beable to listen to the radio (Figure 8)with fixed IP addresses.ProspectsAs already mentioned several times, theEIR is a completely open-ended concept.The software and hardware (via the ex-Figure 6. You can use this program (here running under LinuxKDF) to find the EIR even if its IP address is unknown.elektor - 4/2008
B303.3 VGNDTable 2. Expansion connector K2UsePinSignal UseSDRAM DQML2PB1FreeAddress Bus A24PB3Address Bus A3Address Bus A46PB5Address Bus A5Address Bus A68PB7Address Bus A7Address Bus A810PB9Address Bus A9Address Bus A1012PB11 Address Bus A11Free14PB13 Address Bus A13Address Bus A1416PB15 FreeSDRAM BA018PB17 SDRAM BA1Free20PB19 FIQ, RTC InterruptIRQ0, Ethernet Interrupt22PB21 FreeDataFlash Chip Select24PB23 USB MonitorFree26PB25 FreeFree28PB27 FreeFree30PB29 FreeMP3 Data Select32PB31 MP3 Hardware ResetPower343.3 V PowerNot used36Not usedNot used38NRST Hardware ResetGround40GND GroundInternet radioIf you take a look on the Web, you’ll be astounded to see that Googlepresently finds more than 21 million hits for ‘Internet radio’, so it’s obviously a hot topic. The first experiments with packet-based ‘broadcasts’were carried out as early as 1993, at around the same time as the firstusable browser (NCSA Mosaic) and thus the dawn of the commercialInternet era. Quite early on, ‘real’ radio stations started broadcastingtheir programmes via Internet streaming in addition to conventionalradio waves. Today you can receive tens of thousands of radio programmes with an ordinary Internet connection. In addition to a plethora of highly diverse niche programmes, you can now access nearly allpublic and commercial broadcasters.The term ‘streaming’, which covers near-real-time transmission of timereferenced data such as audio or video content, refers to data streamsthat are as continuous as possible and require the originator to transmita separate stream for each client, which can generate an 3 VJTAGSELVIN4/2008 - elektorpansion connectors) can be extended asdesired, and you can certainly look forward to seeing several articles on thissubject in future issues of Elektor.With regard to software tools, sourcecode and further developments, youshould occasionally check the egniteproject website [1] to see what’s new.There you will find source code and installation files for Windows, Linux andOS X. You will also find links to development environments and other OpenSource projects.There are lots of possibilities. An obvious enhancement would be to add afew buttons and an LCD display so theEIR can be used as a convenient standalone device instead of only via a Webbrowser. And the memory card slot almost cries to be used for a supplementary MP3 player application.(071081-1)traffic volume and thus be a costly proposition if there are a lot of listeners. To keep the data rates within acceptable bounds, a lossy compression is usually used to compress the data before transmission, andthe data is subsequently decompressed by the receiver. This means thatan Internet radio receiver must incorporate a commonly used streamingdecoder, such as MP3, Ogg Vorbis or Real Audio, regardless of whetherit is purely software-based or uses dedicated hardware.As it is not possible to guarantee a constant propagation delay for individual data packets with the HTTP and FTP protocols normally usedon the Internet, the receiver must also have a data buffer with sufficientcapacity, which delays reception by a few seconds and means that it isonly ‘quasi live’. This makes fast zapping between stations impossible.However, thanks to digitalisation this drawback is offset by stable audioquality, extreme (worldwide!) range, and a truly fathomless diversityof programmes. It is also possible to receive previously recorded programmes (missed broadcasts) by means of ‘audio on demand’, whichno conventional radio station can offer.Table 3. Expansion connector K3UsePinSignal UseData Bus D02PC1Data Bus D1Data Bus D24PC3Data Bus D3Data Bus D46PC5Data Bus D5Data Bus D68PC7Data Bus D7Data Bus D810PC9Data Bus D9Data Bus D1012PC11Data Bus D11Data Bus D1214PC13Data Bus D13Data Bus D1416PC15Data Bus D15Bus NWAIT, Open Collector 18PC17Ethernet Hardware ResetMMC Card Detect20PC19MMC Write ProtectFree22PC21Address/Data Bus NWEAddress/Data Bus NRD24PC23Ethernet Chip SelectNot used26Not usedNot used28Not usedNot used30Not usedNot used32Not usedPower343.3 VPowerBoundary Scan Enable36ERASEFirmware EraseUnregulated 5–24 V via38SHDNPower ShutdownR106Ground40GNDGroundReferences andweb links[1] egnite project website:www.ethernut.de/de/hardware/eir/[2] Wikipedia article:en.wikipedia.org/wiki/Internet radio[3] Ethernut and the Kipp Family:Elektor, March 2008, pp 18–21.[4] ARM7 MCU data:www.atmel.com/products/at91/[5] VS1053 data:www.vlsi.fi/products/vs1053.html[6] Link for AT91-ISP.exe:www.atmel.com/dyn/resources/prod documents/Install%20AT91-ISP%20v1.10.exe[7] Windows terminal emulator:ttssh2.sourceforge.jp/23
4/2008 - elektor 17 Elektor Internet Radio (EIR) Listening to radio programmes with the latest ICs 16 bits and a sampling rate of 44.1 kHz, using a data transmission rate as low as 192 kbit/s (or even less) instead of the normal rate of around 1.4 Mbit/s. This means that a buffer with a capa-city of approximately 10 seconds can
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RFID reader on the Elektor Electronics website. Get started The double-sided printed circuit board for the Elektor Electronics RFID reader is shown in Figure 5. It is only possi-ble to reflow solder the reader IC, and so we are making the board available 28 elektor electronics - 9/2006 HANDS-
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ELEKTOR Internet Radio 1.0 Hardware Manual Hardware Expansion Many applications will do just fine with nothing else than the EIR. Or external hardware may be connected to the RS-232 or RS-485 port. However, if more is required, the EIR expansion port is the first choice to add custom designed hardware. Expansion Port
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