The ADMP441 is a high performance, low power, digital output, omnidirectional MEMS microphone with a bottom port. The complete ADMP441 solution consists of a MEMS sensor, signal conditioning, an analog-to-digital converter, antialiasing filters, power management, and an industry standard 24-bit I²S interface. The I²S interface allows the ADMP441 to connect directly to digital processors, such as DSPs and microcontrollers, with-out the need for an audio codec in the system. The ADMP441 has a high SNR and high sensitivity, making it an excellent choice for far field applications. The ADMP441 has a flat wideband frequency response, resulting in natural sound with high intelligibility.
System: Microblaze, AXI, UART
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).
If you are not familiar with LX9 and/or Xilix tools, please visit
http://www.xilinx.com/products/boards-and-kits/AES-S6MB-LX9.htm for details.
Extract the project from the archive file (ADMP441_lx9.zip) to the location you desire.
To begin, connect the PmodMIC2 to J5 connector of LX9 board (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.
To begin, connect the PmodMIC2 to JA connector of Nexys™3 board (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 (../admp441/sw/ADMP441.bit). Launch “data_capture.bat” from the ”../DataCapture” folder.
If programming was successful, you should see messages in the UART terminal.
For reasons NOT depending on Analog Devices, the JTAG connection through which the stored data on the LX-9/Nexys3 is transfered to the *.wav file is very slow. The process takes about 2 hours.
The reference design is a custom I2S interface used to communicate with the device. An interrupt signal is used to tell the user when new data has been read, an also if data was read when WS was low or high.