Some details about the ADSP-21489 peripherals

Hi,

Please find the answers below:

Guillaume wrote:

Hello I am working on  ADSP-21489 EZ-board. I utilize 16-ch PWM for servo ctrl (16pins) , one SPI master working with 4 external slaves (clk, miso,mosi, 4 flags ==>7pins)), another SPIB for load SPI flash (3 pins ) and the UART for GPS com (2 pins). My questions are,

1.  Can ADSP-21489 supply with enough pins for above-mentioned periphrals?
     Except or 14 pins of DPI, can we multiplex all other signals to external port?

Mitesh>> Yes, all the 16 PWM signals can be mapped to the ADDR23-8 pins of the external port. For more details, please refer page 24-30 of the ADSP-214xx HRM Rev 1.0.

2. The PWM module has four groups of four PWM outputs each, for a total of 16 PWM outputs.  Can we config the 16-ch PWM to be independent?

Mitesh>>Yes, all the 16 channels can be configured independently. Bit 1 of the PWMCTLx register can be cleared to disable the paired mode and thus making the signals AH/BH and AL/BL independent.

3. Using the EZ board,  I practiced to burn my software in SPI flash and run the code without any trouble. I will build my own PCB board and only use the on chip SRAM (5Mb). If I select a 32Mb SPI flash (ROM) with the same brand of that of EZ-board, I would like to know whether I can reuse the loader file.

Mitesh>> Yes, the same loader file can be re-used for a bigger FLASH as well. In fact, the ldr file will remain the same for any type of SPI FLASH. You just need to make sure that it is burnt starting from the byte address 0x000000 of the FLASH.

Thanks in advance

Hi Mitesh, thanks for your help. I am still new in this area and didn’t have time to look through the manual in detail.

If I use the 176-lead adsp-21489, I will select the following pins:

1. SPI master to 4 external SPI slave (3 DPI pins: CLK, MOSI, MISO; 4 pins using the external port for Flag1-4) 

1. SPIB master to SPI flash (3 DPI pins: CLK, MOSI, MISO)

1. 3 DPI pins for UART

1. 16 pins using external-port for 16-cha PWM ctrl (ADDR8~ADDR23)

For the above configuration, 9 DPI pins and 20 external-port pins are used. The number of DPI pins is sufficient for my application. Is the configuration correct?

However, if I use 100-lead adsp-21489, it seems that the above-listed configuration cannot be built-up, because the 100-lead packages do not contain an external port. Is my conjecture correct?

I have successfully tested my16-cha PWM ctrl on external-port using the 21489 EZ-board.

Best Regards

Hi,

Yes, the DPI and external port pin selections look feasible to me.  Also,, you are correct that this configuration is not possible on 100 pin package without the external port. However, I had following questions:

1) You mentioned that you will be using SPIB as master to SPI FLASH. Please note that SPI FLASH boot is supported only via SPI and not SPIB. So, in case you want to use SPI FLASH for booting, you may have to use SPI and not SPIB. Also, please note that when using SPI master boot mode, the DPI pins which can be used for booting are fixed (DPI1 - MOSI, DPI2 - MISO, DPI5- chip select, DPI3 -SPICLK). Please make sure that you  take care of this fact before designing the board.

2)  Why do you want 3 DPI pins for UART?

Thanks,

Mitesh

Hi Mitesh,

Sorry for my late response. Regarding your 2 questions,

1) Your reminder about the SPI master boot mode is correct and I will take it into account for my PCB design. Your pointer has saved me much time.

2) Yes, the UART should use 2 DPI pins instead of 3 pins

Thanks for your invaluable and timely help.

Regards

Hi,

Thanks. I shall assume this thread closed as of now. Please let me know if you need further help.

Regards,

Mitesh