SD Card Data Logger Senior Design II Final Presentation April 21, 2011

Team Advisor: Dr. Patrick Donohoe James Felkins (EE) Team Leader, Web Design, Test Board Harry Corey (EE) Test Cases, Hardware Design, Part Procurement Brendan Babiak (EE) Prototype Construction, Buffering Scheme, MDDFS Jaron Martin (CPE) Command Set, SPI/UART Input, MDDFS

Introduction to Project problem/solution tech./practical constraints System Overview high-level system design software solutions Hardware Design power PCB Testing subsystems features Questions

The S-Drive is an OEM module that accepts data through a serial connection and saves it to an SD card.

SD cards are a viable storage medium with unique advantages but involve complex overhead.

The S-Drive will handle the unwanted overhead and make SD cards a more desirable solution.

NameDescription CommunicationThe device uses UART and SPI data connections. Voltage The device supports an input voltage between 3.3 or 5 V. Current Draw The device draws a maximum current of 250 mA in active mode and less than 10 uA in sleep mode. Storage Medium The device interfaces with a standard size, 32 x 24 x 2.1 mm SD card. MemoryThe device supports all SD cards up to 32 GB.

The device must cost less than $60. CompetitorPrice VDRIVE2$24.50 [4] Logomatic v2$59.95 [3] Avisaro M € (~$133) [2] [2] [4] [3]

The device must easily fit and integrate into other systems. Provided on a PCB No larger than 5 in 2 Easily mountable

Software Implementation -Microchip’s MDDFS library -Command Interface

Size constraint met

Command Set Open File for Append 1 Opens the file LOG1.TXT for appending. Only use if no file is currently open. Returns 1 if successful, else returns error code. Creates the file if it does not exist. a Open File for Read 12 - ? File name followed by \n character to represent the end of the name. File pointer will start at the beginning of the file. Use only if no file is currently open. Returns 1 after each byte if OK, else returns error code. oFile Name Close File 1 Closes the file so that another file can be opened or the SD Card can be safely removed. Use only if a file is open in either write or read mode. Returns 1 if successful, else returns error code. c Write Data [4-257] The S-Drive will append the next NumBytes received to the end of the file. Use only if the file is opened in write mode. Returns 1 after each byte if OK, else returns error code. w# of BytesData Read Data 1 Each time the r command is is received, the next byte in the file is returned and the file pointer moves one by byte. Use only if the file is opened in read mode. Returns the next byte in the file. If at EOF, starts over at beginning of file. r Move Read Pointer 12 Moves the read pointer NumBytes without replying with each byte of data. Use only if file is open in read mode. Returns 1 if sucessful, else returns error code. m# of Bytes Flush Buffer 1 Flushes the write buffer. Use to flush the buffer if you do not want to wait for the buffer to automatically get written. Use only if file is open in write mode. Returns 1 if successful, else returns error code. f Sleep 1 Forces the S-Drive to enter sleep mode. s Big File 12 - ? ? Allows for long or unknown lengths of data to be written to SD card. Use only if the file is opened in write mode. Returns 1 after each byte if OK, else returns error code. End this command by sending a NULL byte. bData NULL

Data size not pre-specified Binary files may contain all possible byte values Toggle wake pin to signal EOF

SPI & UART multiple baud rates config.txt file jumper determines mode

Flow Control 2.3 kB each buffer READY pin

Enters ‘Sleep Mode’ Enters mode via SLEEP command Dedicated WAKE signal Uses READY pin while re-initializing SD card

8 wires UART/SPI TX & RX use same lines

Standard-sized SD cards Supports adapters for mini- and micro- SD cards

Accepts 3.3 and 5 V inputs Power mode determined by jumper 5 V mode uses a low-dropout LR

Current draw SD card has own power rail SD card is uses ~250uA while inactive Sleep mode cuts power to SD card Implemented with a low-dropout LR

Power (V)Inactive Current Draw (mA) Active Current Draw (mA) Sleep Current Draw (uA) Constraint Met? Yes N/A

Baud RatePower(V)Inactive Current Draw (mA) Sleep Current Draw (uA)

Practical Constraints Small Affordable parts Mountable

Issues Disjoint ground planes SPI buses fused Issues corrected for web-site

SPI MasterSPI Slave Logic Analyzer

Realterm

Operational modes 8 possible combo’s

Python Tool Handles semantics Very slow Used to test robustness Better demo

Reading large file from SD card Took appx. 1 hour w/ Python tool for 20kB File perfectly copied Testing done in all modes ~3.5 kbps reading and writing

Sending/Receiving a large file: Intermediate MCU sends 5 million chars Data rate ~15kB/s

Command Functions All functions do their job Improper commands are ignored (no crash)

IssueConstraintActual SpecMet? Comm. InterfaceUART & SPI Voltage3.3 & 5 (V) Current Draw<10 uA (sleep)~4.5 uA Storage MediumStandard SD SD Card SizeUp to 32 GB

[7] Microchip, “PIC24F Family Reference Manual, Sect. 21 UART,” Microchip Technology Inc., January 26, [Online]. Available: [Accessed September 14, 2010]. [8] Microchip, “PIC24F Family Reference Manual, Sect. 23 Serial Peripheral Interface (SPI),” Microchip Technology Inc., March 22, [Online]. Available: [Accessed September 14, 2010]. [9] STEC, “SLDSxxxBS(I)U Data Sheet,” STEC Inc., March [Online]. Available: inc.com/downloads/flash_datasheets/SLSDxxxB_I_U pdf. [Accessed September 14, 2010]. inc.com/downloads/flash_datasheets/SLSDxxxB_I_U pdf [10] Sparkfun Electronics, “Logomatic v2 Serial SD Datalogger,” On-Line Store,2010.[Online].Available: p?products_id=8627. [Accessed:September 14, 2010]. [11] C-ONE Technology Corp., “Wide Temperature Industrial SD Card Product Specification,” May [Online]. Available: [Accessed: September 14, 2010].