The ADT7420 is a high accuracy digital temperature sensor offering breakthrough performance over a wide industrial range, housed in a 4 mm × 4 mm LFCSP package. It contains an internal band gap reference, a temperature sensor, and a 16-bit ADC to monitor and digitize the temperature to 0.0078°C resolution. The ADC resolution, by default, is set to 13 bits (0.0625°C). The ADC resolution is a user programmable mode that can be changed through the serial interface.

HW Platform(s):

• Spartan-6 LX9 Microboard (Avnet)
• Nexys?3 Spartan-6 FPGA Board (Digilent)
• Avnet ZedBoard
  

The bit file provided in the project *.zip file combines the FPGA bit file and the SDK elf files. It may be used for a quick check on the system. All you need is the hardware and a PC running a UART terminal and the programmer (IMPACT).

• Spartan-6 LX9 Microboard (Avnet)
• Nexys?3 Spartan-6 FPGA Board (Digilent)
• Avnet ZedBoard
  
• PmodTMP2 (Digilent)

• Xilinx ISE 14.4 (Programmer (IMPACT) is sufficient for the demo and is available on Webpack).
• A UART terminal (Tera Term/Hyperterminal), Baud rate 115200 for the Avnet LX-9 Microboard and ZedBoard or 9600 for the Digilent Nexys?3 Board.

Extract the project from the archive file (ADT7420_.zip) to the location you desire.

To begin, connect the PmodTMP2 to J5 connector of LX9 board, pins 3 to 6 (see image below). You can use an extension cable for ease of use. Connect the USB cable from the PC to the USB-UART female connector of the board for the UART terminal. The board will be programmed through its USB male connector.

Extract the project from the archive file (ADT7420_.zip) to the location you desire.

To begin, connect the PmodTMP2 to JA connector of NEXYS3 board, pins 3 to 6 (see image below). You can use an extension cable for ease of use. . Connect the USB cables from the PC to the board, one for programming (Digilent USB device) and one for the UART terminal (FT232R USB UART).

To begin, connect the PmodTMP2 to JC1 connector of ZedBoard (see image below). You can use an extension cable for ease of use. Connect the USB cables from the PC to the board, one for programming (Digilent USB device) and one for the UART terminal (FT232R USB UART).

Start IMPACT, and double click “Boundary Scan”. Right click and select Initialize Chain. The program should recognize the Spartan 6 device (see screenshot below). Start a UART terminal (set to appropiate baud rate) and then program the device using the bit file provided in the project *.zip archive, located in the “sw” folder (../adt7420/sw/ADT7420.bit).

Run the download.bat script from the “../bin” folder downloaded from the github (see the links in the download section of the wiki page). The script will automatically configure the ZYNQ SoC and download the *.elf file afterwards.

If programming was successful, the Main Menu will apear in your UART terminal, as seen in the picture below. There are 10 options. Pressing [t], [r], [h], [l], [c], [y], [f], [s], [m] or [q] key will allow you to select the desired option.

Read Temperature will start printing temperatures read from the ADT7420. Pressing [m] at any time will stop the process and return to the Main Menu.

Set Resolution allows choosing between 16 bit or 13 bit accuracy. The desired resolution is selected by pressing [1] or [2].

Set THigh is used to set the upper temperature limit (for internal comparison purposes - when used as thermostat). The value entered is between 0x0000 and 0x1FFF for 13 bit resolution or between 0x0000 and 0xFFFF for 16 bit resolution. If entering less than 4 characters, you must press [Enter] in order to validate the result. If entering 4 characters, the result is automatically validated.

Set TLow is used to set the lower temperature limit (for internal comparison purposes - when used as thermostat). The value entered is between 0x0000 and 0x1FFF for 13 bit resolution or between 0x0000 and 0xFFFF for 16 bit resolution. If entering less than 4 characters, you must press [Enter] in order to validate the result. If entering 4 characters, the result is automatically validated.

Set TCrit is used to set the critical temperature limit. The value entered is between 0x0000 and 0x1FFF for 13 bit resolution or between 0x0000 and 0xFFFF for 16 bit resolution. If entering less than 4 characters, you must press [Enter] in order to validate the result. If entering 4 characters, the result is automatically validated.

Set THyst is used to set the hysteresis. The value entered is between 0x0000 and 0x000F. If entering less than 4 characters, you must press [Enter] in order to validate the result. If entering 4 characters, the result is automatically validated.

Set Fault Queue allow setting the number of fault events that have to take place before issuing an interrupt signal. Choosing the number of faults is done by pressing [1] to [4].

Display Settings will display the current settings for the device (Resolution, THigh, TLow, TCrit, THyst, Number of faults, Alert Mode, CT pin and INT pin active values).

Pressing [m] will display the available options (main menu).

Pressing [q] will exit the application.

The reference design is a SPI interface used to communicate with the device. The software programs the ADT7420s internal registers, and afterwards reads desired data from the device and prints it via UART.

// Select between PS7 or AXI Interface
#define USE_PS7 	 1
// SPI used in the design
#define USE_SPI		 0
// I2C used in the design
#define USE_I2C		 1
// Timer (+interrupts) used in the design
#define USE_TIMER	 0
// External interrupts used in the design
#define USE_EXTERNAL     0
// GPIO used in the design
#define USE_GPIO         0

• ask questions about the FPGA reference design
• Example questions:

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