Design notes for the ScoutFly. Will not be in any real order or organisation. Just a dump of ideas as they come along. Contact kwoo@ to discuss things. Try not to modify this unless you have been given permission to.

Note: Alot of this documentation is out of date due to the switch to using the gumstix. Please verify that it is correct before proceeding.


  • If GPI_01 determines what device to boot from
    • if high, boot from UART5
    • if low, boot from (in this order) SSP0 -> EMC (CS0) -> NAND


ARM UART Connection Notes
1 AVR UART 0 Size level shifters for .5Mbit/s max
2 XBee
5 FTDI USB For Booting over serial, OS bootstrapping



Followed the usual guide:


Power Supplies

Source Charge Logic Power Polarity Powers Motors
USB no 1 no
charging station contacts (12V) yes 2 no
Battery (dual cell lion) n/a 3 yes

Reverse polarity problems

  • We only need to worry about problems coming in on the battery

Push Button On

  • Separate chip to handle it
    • LTC2952
    • Informs the processor of shutdown starting and allows processor to control when it happens
    • Integrated Power OR (see below)

Power Controllers

  • We need to select which source to use when multiple are plugged in. We can use a PowerPath IC to handle this.
    • Thinking of LTC4412
      • Single source, the primary isn't present the secondary will kick in
    • or LTC4416
      • Dual source, if the primary isn't present the secondary will be switched to
    • The LTC4412 requires us to use one less FETs but the switch time is slower (175us vs 60us)
    • LTC1473
      • Dual source, but allows us to use a DC bypass. This could save us a chip
      • We need logic to decide which battery to take though
  • LTC4412 has the least need for extra components and is cheaper per chip. We need the same amount of chips regardless of which we choose.
  • We only need to do 1 level now. We get an extra level from the LTC2952


  • Max 745
    • Expensive...$8.76 in our quantities
    • Can do 1-4 cell batteries, 4A max, less external components
    • The 2A charging requirement took out most of the chips that can do 2+ cells
    • This actually can do thermal shutdown if the battery OR itself gets too hot
    • Less external components than the cheaper chips

Power Domains

Voltage Load Regulator What's on it
7V 3.5A (when all 5 motors stall) Unregged Steppers, drive motors
5V 77.2mA LT3507 AVR, Quadrature Encoders, Sonar, Cliff Sensor, Motor Drivers
3.3V 325mA LT3507 XBee, VDD_AD (A2D convertor, note we need a lowpass filter, LC), VDD_IOB, VDD_IOD (these two are for ethernet), Accelerometer, Gyro, Orbs
1.8V 40mA LT3507 DDR SDRAM, NAND FLASH, VDD_IOC (this is the flash pins), VDD_EMC (sdram pins)

VDD_IOA, VDD_IOB, VDD_IOD (1.7 - 3.6), these need to be set to whatever we're interfacing to

The current load numbers are probably undershooting so add some factors of safety because I did a lot of rounding and guessing. Note that these current numbers don't reflect the draw of external components. Most notably support chips such as the RAM, FLASH, micro SD, PHY, etc. They will probably be the heaviest draw on the 3.3V lines though.


  • LT3507 - Triple buck converter, adjustable, 1 LDO
    • Can use the actual outputs to drive 5V, 3.3V, and 1.2V



SD Card Interface

Stolen from:

PIN# Pin Name
1 Data 2
2 Card Detect / Data 3
3 Command
4 Vdd (2.7V - 3.6V)
5 Clk
7 Data 0
8 Data 1
This is the card from the bottom. The leftmost in is the furthest from the edge
1 2 3 4 5 6 7 8

You need to initiate the card through several steps. Here is the specification:

Parts list

New for v2 Parts

Linear LTC3633 Dual Buck Converter We only need 3.3V and 5V now, this does 3A on each channel with integrated fets. Just need inductors and some caps TSSOP-28 newark datasheet
TI TXB0108 Hex Level shifter, bi directional For 1.8 to 3.3 or 3.3 to 5.5 TSSOP-20 digikey" datasheet
Worth 748421245 Balun For the wireless antennae, be careful with layout ??? datasheet digikey
Microchip TC1015-1.8VCT713 1.8V Linear Regulator 3.3V to 1.8V for levelshifting to the ARM SOT23-5 datasheet" digikey
TDK RLF7030T-1R0N6R4 1uH Inductor For the 3.3V switching regulator n/a datasheet digikey
TDK RRLF7030T-1R5N6R1 1.5uH Inductor For the 5V switching regulator n/a datasheet digikey
TI SN74LVC1G11 3 input AND Gate For AVR reset since we have 3 reset sources. Eliminates the need to use a bunch of resistor to prevent drive fights and marginally making it in terms of the correct voltages to turn off datasheet digikey
Panasonic PCE3294CT-ND 47uF AlElec Cap Input caps for the regulator 5/3.3 Panasonic size "C" datasheet digikey"
Cap 22uF 1210, low esr, for output cap for regulator
Atmel ATMEGA128RFA1 AVR Micro with RF component Stupid atmel keeps pushing the release date back 64qfn "digikey": datasheet
Alegro A3967 Stepper Controller The last one only operates at a 8V min, this operates at 4.5V min for the supply 24-SOIC "digikey": datasheet
Part Function Notes Package Digikey Datasheet
MAX745 1-4 Cell Lith Ion Charger Does 2A+ that we wanted, most can only handle 1.5A for charging. A little expensive but allows a wide variety of input voltages and is flexible if our power situation changes 20-SSOP digikey datasheet
LT3507 Logic Power Supply Triple buck converter with a built in LDO. We need one more LDO to handle the 5th voltage domain we have. This gives us a lot of power for the accessories...likes 1-2A+ 38-QFN digikey datasheet
LTC2952 Push Button Controller Initiates boot up and shut down via push button, has a power-path integrated for ORing of power supplies to be used with LTC4412 20-QFN digikey datasheet
LTC4412 Power OR Controller We use these to prioritise the different power inputs. We cascade them to form a tree TSOT-23-6 digikey datasheet
Vishay/Siliconix SI5401DC-T1-E3 P-Channel MOSFET, 20V, 5.2A for the power-channel stuff, takes our max power consumption 1206-8 ChipFET digikey datasheet
IR IRF7303TRPBF Dual NFET, 30V, 4.9A For the battery charger 8-SOIC digikey datasheet
Fairchild MBRS340 Schottky Diode 40V, 3A For the MAX745 charger, LT3507 diodes DO-214AB digikey datasheet
Micro Comercial Co 1N4148W-TP Switch Diode 100V, 150mA For LT3507/MAX745 Boost diode SOD-123 digikey datasheet
National DP83848JSQ/NOPB Ethernet PHY Ethernet PHY -> MII/RMII Interface 40-LLP digikey datasheet
Maxim DS2786G+ Lithion Gas Gauge Need to do that nasty hack 10-TDFN digikey datasheet
Coiltronics DR74-4R7-R 4.7uH, 3.34A Max Inductor Shielded, 25mOhm DCR, 20% Tolerance N/A digikey datasheet
Taiyo Yuden NR6045T3R0N 3uH, 5A Inductor Shielded, 24mOhm DCR, 30% Tolerance N/A digikey datasheet
Coiltronics DR125-220-R 22uH, 3.7A Max Inductor Shielded, 39.6mOhm DCR, 20% Tolerance N/A digikey datasheet
Pulse J00-0064NL RJ45 Jack with Magnetics Smaller than the other one by a good amount but lacks LEDs RJ45 digikey datasheet
Hirose UX60-MB-5S8 USB Mini-B Connector, Female For FTDI N/A digikey datasheet
Steward MI0805K400R-10 Ferrite Bead For USB 5V on FTDI 0805 digikey datasheet
AVX Corp KC3225A50.0000C30E00 50MHz, 3.3V oscillator For Ethernet PHY, using RMII so we needed a clock 2x as fast as when we used MII N/A digikey datasheet
ECS ECS-.327-12.5-34B 32.768kHz RTC Crystal For the RTC, smaller than the old one N/A digikey datasheet
NDK NX3225SA-16.000000MHZ Crystal, 16MHz ATMega128 Clock N/A digikey datasheet
Bourns Inc MF-SM200-2 Resettable Fuse Blows over 4A N/A digikey datasheet
STMicro LISY300AL Gyro 28-LGA sparkfun datasheet
Analog Devices ADXL345 Accelerometer LGA sparkfun datasheet
Linx Tech ANT-2.45-CHP-T SMT Chip Antennae Look at sheet for layout N/A digikey datasheet
Toshiba TB6612FNG Dual Motor Driver 24-SSOP digikey datasheet
Fairchild MMPQ3904 Quad NPN 200mA Ic, Low Vce Sat, for driving LEDs and whatnot 16-SOIC digikey datasheet
China Young Sun LED Technology Co. YSL-R596CR3G4B5C-C10 Tricolor RGB LED N/A sparkfun datasheet
Diode ZDT1053TA Dual BJT NPN, 5A, 2.5W Motor Current limiters, smaller than previous ones. Hopefully won't burn up from the power SOT223-8 digikey datasheet
NXP PCA9306DP,118 2 Channel lever shifter Supposed to be for I2C but also using it for all 3.3<->5V translations 8-TSSOP digikey datasheet
Vishay SI3493BDV-T1-E3 MOSFET, P-Channel, 20V, 8A Reverse charger protection 6-TSOP digikey datasheet
Diodes Inc. DMP2066LDM-7 MOSFET, P-Channel, 20V, 4.6A Reverse Battery protection, logic level SOT26 digikey datasheet
Kingbright APT1608Q
LED, Blue, 100mcd, 3.3V, 20mA Power LEDs 0603 digikey datasheet
Kingbright APG1608SURKC/T LED, Red, 320mcd, 2V, 20mA 0603 digikey datasheet
Kingbright APG1608CGKC/T LED, Green, 60mcd, 2.1V, 20mA 0603 digikey datasheet
SMT Button SMT Button N/A sparkfun datasheet
Diodes DMMT3906W-7-F PNP Transistor, Dual, 200mW For orbs SOT363 digikey datasheet
On Semiconductor NL27WZ14DFT2G Dual Schmitt Trigger, Inverting Button Debouncing, we were only using at most 4 of 6 of the hex inverters and this is smaller SOT-363 digikey datasheet
Keystone 3000 12mm coin cell battery holder for the rtc clock N/A newark datasheet
Taiyo Yuden TMK107BJ104KA-T 0.1uF ceramic cap, X5R 0603 digikey datasheet
TDK C1608X5R1C474K 0.47uF cermaic cap, X5r 0603 digikey datasheet
TDK C1608X7R1E473K 0.047uF ceramic cap, X7R 0604 digikey datasheet
AVX 0805YD106KAT2A 10uF ceramic, x5R 0805 digikey datasheet
TDK C3216X5R0J156M 15uF ceramic cap, x5R 1206 digikey datasheet
Murata GRM31CC80G476ME19L 47uF ceramic cap, x6s 1206 digikey datasheet
Murata GRM188R71H102KA01D 1000pF ceramic cap 0603 digikey datasheet
Murata GRM1885C1H202JA01D 2000pF ceramic cap 0603 digikey datasheet
Kemet C0603C103K5RACTU 0.01uF ceramic cap 0603 digikey datasheet
Murata GRM188R71A105KA61D 1uF ceramic cap 0603 digikey datasheet
Vishay 293D104X9035A2TE3 0.1uF tantalum cap 1206 digikey datasheet
Kemet T499A224K035ATE18K 0.22uF tantalum cap 1206 digikey datasheet
Kemet T491A106K010AT 10uF tantalum cap 1206 digikey datasheet
Johanson Tech 251R14S180GV4T 18pF, 2 % tolerance ceramic cap 0603 digikey datasheet
Yageo CC0603KRX7R6BB224 0.22uF ceramic cap 0603 digikey datasheet
Kemet C0805C475K9PACTU 4.7uF ceramic cap 0805 digikey datasheet
Murata GRM1885C1H431JA01D 430pF ceramic cap 0603 digikey
Kemet C0603C100J5GACTU 10pF, ceramic cap 0603 digikey datasheet
Taiyo Yuden HK16081N5S-T 1.5nH inductor Wireless amp antennae filter 0603 digikey datasheet
TDK C1608C0G1H010B 1pF ceramic cap 0603 digikey datasheet
ST Micro BAS69KFILM Diode, 100mA For RTC Battery SOD523 digikey datasheet
Microchip MCP1702T-5002E/CB 5V LDO, 250mA For gas gauge power SOT23 digikey datasheet
Panasonic ERJ-6BWFR010V Resistor 0.01 Ohm, 1%, 1/4W This is 5A max exactly, we should not exceed that, for the current sense resistor on the gas gauge 0805 digikey datasheet
Assmann Electronics AU-Y1006-2-R USB A Conenctor SMT with 2 throughholes for mounting N/A digikey datasheet
CTS 767143202G Resnet, 2K, 7 Isolated For Debug LEDs 14-SOIC digikey datasheet
CTS 767141680G Resnet, 68, 13 Bussed For debug LEDs 14-SOIC digikey datasheet
Stackpole CSRN 1 0.1 1% I 0.1 Ohm, 1W Resistor For MAX745 Sense resistor, charge current goes through it at 2A 2010 digikey datasheet
Stackpole CSRN 2 0.5 1% I 0.5 Ohm, 2W Rsistor For the Motor driver current limiter 2512 digikey datasheet
Comchip Technology CDSU101A Diode, 80V, 100mA For dropping the RTC voltage 0603 digikey datasheet
CR1220 3.0V, CR1220 Coin Cell battery, lithium RTC Backup/primary battery CR1220 allspecturm N/A

Removed Parts

NCP584 Logic Power Supply, 1.2V 1.2V fixed LDO, 200mA max current. This handles the 1.2V domain. About a factor of 2.5 more current than we need? SOT23-5 digikey datasheet
NXP Semiconductor BSS83,215 MOSFET, N-Channel, 10V, 50mA I2C Level Shifters SOT143B digikey datasheet
Maxim DS2777G+ Lithion Gas Gauge Gas gauge and reverse battery protection. Note that min quantity is 34 and there is 17 day lead time 14-TFDN newark
Epson Toyocom Corporation MC-405 32.7680K-A0 Crystal, 32.768kHz For the RTC N/A digikey datasheet
ECS Inc. ECS-250-20-5G3XDS-F-TR 25MHz Crystal For the Ethernet PHY chip N/A digikey datasheet
Micron MT46H32M16LFBF-5:B DDR SDRAM, 512MB listed in the datasheet for compatability 60-VFBGA digikey datasheet
ON Semiconductor MJD31CG NPN BJT Transistor, 3A, 100V Motor current limiter DPAK digikey datasheet
Bel Fuse Inc 0826-1L1T-57-F 10/100 RJ45 Jack Includes LEDs and Magnetics N/A digikey datasheet
Lumex Opto SSA-LXB525SRD 5 Seg LED Bar, Red 1.7V, 30mA, For ARM debug N/A digikey datasheet
Lumex Opto SSA-LXB525GD 5 Seg, LED Bar, Green 2.2V, 25mA, For ARM debug N/A digikey datasheet
TI SN74AHC14DR Hex Schmitt Trigger Button debouncing 15-SOIC digikey datasheet
Tyco 1981584-1 USB Micro A/B Connector Female end, SMT, might only be USB 1.0? It isn't that fake smt where there are throughole tabs which eagle can't seem to handle cleanly N/A digikey datasheet
ECS ECS-250-20-30B-TR 25MHz Crystal For the Ethernet PHY, doesn't meet load capacitance numbers but none of the crystals seem to, this is smaller than the old one N/A digikey datasheet
NXP LPC3240 ARM9 Main Processor FBGA digikey datasheet
ST Micro NAND01GW3B2CZA6E NAND Flash, 1GB Cheap and its fits our requirements in terms of connectivity 63-VFBGA digikey datasheet
On Semiconductor NSS30071MR6T1G NPN Transistor, 30V, 700mA For the LDO on the LT3507 SC74-6 digikey datasheet
Panasonic EEF-CD1C4R7R 4.7uF alelec cap EIA-7343 digikey datasheet
TDK C1608X5R1A225M 2.2uF ceramic cap, x5r 0603 digikey datasheet
Kemet C0603C221K5RACTU 220pF ceramic cap 0603 digikey datasheet
TDK C1608X7R1H152K 1500pF ceramic cap 0603 digikey datasheet
TDK C1608X7R1H472K 4700pF ceramic cap 0603 digikey datasheet
AVX 06031A330FAT2A 33pF ceramic cap, 1% tolerance 0603 digikey datasheet
Murata GRM2165C1H392JA01D 3900pF, 5% ceramic cap 0603 digikey datasheet
AVX 08052A151JAT2A 150pF, 5% tolerance, ceramic cap 0805 digikey datasheet
ST Micro STOTG04EQTR USB-OTG Phy For the USB Controller. Handles OTG, device, and host 24-QFN digikey datasheet
Atmel AT91SAM9260 ARM9 Has pretty much all of the NXP variety but in a qfp package 208-qfp digikey datasheet
Atmel ATMEGA128 Coprocessor The standard and L variants are discontinued as of summer 2009, but no one carries the replacement yet. The new variant "A" runs at less power and is totally pin compatible 64-QFN digikey datasheet
FTDI FT232R USB<->Serial Converter 32-QFN digikey datasheet
Micron MT48H32M16LFBF-75:B TR 512MB SDRAM, Mobile, 1.8V, 133MHz There are issues using DDR on the ARM due to a bad CLKN pin, SDRAM is "safer", clocking it at 100MHz 54-VFBGA digikey datasheet
Atmel AT45DB16 16Mbit Dataflash, SPI Used to boot the ARM, only the AT45 family is supported, this is the only size in quantity 8-SOIC mouser datasheet
3M 2908-05WB-MG Micro-SD Card Holder SMT, Right angle, push/push micro sd card holder N/A digikey datasheet--
Atmel AT86RF231-ZU Zigbee Chip 32-QFN digikey datasheet
TI CC2591RGVR Antennae Amp 16-QFN digikey datasheet
Allegro Microsystems A4983SETTR-T Stepper Motor Driver 28-QFN digikey datasheet

App Notes