ADAU1452 code download

Question

Dear Sir, 
 We are starting a project with ADAU1452 Dsp. Now we encounter a problem 
 when we down the Dsp code(which from export file) through the external MCU. 
 
 The system is setuped by ADAU1452 DSP and one MCU. MCU will init the DSP and 
 down the DSP code by SPI bus. The system initialization as following: 
 
 1. System power up(both DSP and MCU) 
 2. MCU will reset DSP by control DSP reset pin, delay 1ms then release the DSP reset pin 
 3. MCU do 3 times dummy SPI write to make the Dsp enter SPI slave port. 
 4. Delay 400ms 
 5. Down the Dsp code by "default_download_IC_1()" function. ( which from export file) 
 
 We confuse in the step 4: we must need delay about 400ms, then we can download the Dsp code successfully. 
 If no this delay or the delay time is short, we can not download the Dsp code successfully. 
 We assure the DSP selfboot pin has pull low(disable selfboot). This is very strange. 
 
 Would you give your kindly support about this? 
 
 Best Regards 
 RN

rongnan · Accepted Answer

Hello, Dave 
 
 Thank you for your quickly response! 
 
 We find the root cause about this issue(hardware design issue): 
 
 Root cause: 
 The MCU control the ADM811 pin 3(MR), and the ADM811 pin 2(Reset) connct to the ADAU1452 reset pin. 
 When we pull high the ADM811 pin3(MR), the ADM811 pin2(Reset) have the time delay output(refer the attachment 
 ADM811 datasheet). so we have to wait the delay time to get the successfully code download. 
 
 Action: 
 Delete the ADM811 and let the MCU control pin connect the ADAU1452 reset pin directly, then all is well as we expect.. 
 
 Thanks again. 
 RN