SD Loader

SD/Serial Loader

• Send/receive files to/from SD card from/to serial port
• Menu driven program

Features

• Supports SD cards up to 32GB
  • FAT32 formatted
• Serial interface
  • Full hardware Handshake support

Cards

• Constructed out of existing Land Boards cards
• QT Py board
  • Either the SAMD board or RP2040 board versions
  • QT Py Breakout board or QTPy49
• SD CARD X49
• MyMenu
  • MCP23008 I2C interface
  • OLED
  • 5 Pushbuttons
  • 3 LEDs
• Optional Level Shifter mounted on GRID49 card
  • Used for legacy 5V system targets

QT Py Breakout

• Power via USB C cable

SD CARD X49

MyMenu

Level Shifter (Optional)

• Use for "legacy" 5V Serial systems
  • Not used for 3.3V systems
• Convert 3.3V QT Py Tx/Rx/RTS/CTS to "legacy" 5V
• 4-channel I2C-safe Bi-directional Logic Level Converter

QT Py Breakout Card (on GRID49 card) Cabling

• QT Py uses (2) 1x7 male headers for signals
  • Cut off 1 set of holes of (2) female housings to make 1x7 female headers
• SD Card uses (1) 1x8 header
• MyMenu uses (1) 1x5 header
• QT Py uses 2x8 header for 3.3V and Ground
  • Use 2x3 female housings
• 40mm cables to Host Target

QT Py Breakout Card to MyMenu Cabling

QT Py	SIGNAL	MyMenu	COLOR
1 (A0)	INT(D6)	P2-5	GRY
5 (SDA)	SDA	P2-3	WHT
6 (SCL)	SCL	P2-4	BRN
GND	GND	P2-1	BLK
VCC	+3.3V	P2-2	RED

QT Py Breakout Card to SD_CARD_X49 Cabling

QT Py	SIGNAL	SD_CARD_X49	COLOR
03 (A3)	SS*	J1-5	GRY
09 (SCK)	SCK	J1-3	BLU
10 (MI)	MISO	J1-2	BRN
11 (MO)	MOSI	J1-4	WHT
GND	GND	J1-1	BLK
VCC	3.3V	J1-8	RED

QT Py Breakout Card to Host Serial

QT Py	SIGNAL	COLOR
GND	GND	BLK
7 (TX)	TX	WHT
8 (RX)	RX	BRN
2 (A1)	RTS*	GRY
3 (A2)	CTS*	ORA

QT Py Card Cabling

• QT Py Card has function specific headers

Software

• Runs on Arduino Nano

Human Interface Design (HID)

• Menu driven
  • MyMenu card driver
• OLED display
  • ug2 u8x8 OLED display driver software

SD Card

• Library
• Example files

SD Card Library

• SD Card library
  • The SD library allows for reading from and writing to SD cards, e.g. on the Arduino Ethernet Shield
  • Based on sdfatlib
  • The library supports FAT16 and FAT32 file systems on standard SD cards and SDHC cards
  • It uses short 8.3 names for files
  • The file names passed to the SD library functions can include paths separated by forward-slashes, /, e.g. “directory/filename.txt”
  • Because the working directory is always the root of the SD card, a name refers to the same file whether or not it includes a leading slash (e.g. “/file.txt” is equivalent to “file.txt”)
  • As of version 1.0, the library supports opening multiple files.
  • The communication between the microcontroller and the SD card uses SPI, which takes place on digital pins 11, 12, and 13 (on most Arduino boards) or 50, 51, and 52 (Arduino Mega)
  • Additionally, another pin must be used to select the SD card
  • This can be the hardware SS pin - pin 10 (on most Arduino boards) or pin 53 (on the Mega) - or another pin specified in the call to SD.begin()

SD Card Example Code

• SD Card example Code
• Read and Write File example
• Read Card Information
• Read a file from a SD card using the SD library and send it over the serial port
• Create and destroy a file on a SD card
• List the files available in the directory of the SD card

SD Card Connections

 ** SCLK - CLK - pin 13
 ** MISO - SDI - pin 12
 ** MOSI - SDO - pin 11
 ** SS - CS - depends on your SD card shield or module.

Serial

• Serial Reference
• Serial.begin(speed)
• Serial.available()
  • Get the number of bytes (characters) available for reading from the serial port.
  • This is data that’s already arrived and stored in the serial receive buffer (which holds 64 bytes).
  • Turn off/on receive handshake based on Serial.available() count and storage
• Serial.write()
  • Writes binary data to the serial port
  • This data is sent as a byte or series of bytes
  • To send the characters representing the digits of a number use the print() function instead.
  • Syntax

Serial.write(val)
Serial.write(str)
Serial.write(buf, len)

References

• XMODEM Protocol
• S record format