Hello,
I am trying to boot DM6435 using SPI or UART connected to a host processor. Let's start with UART: we are not using HW handshaking and this seems to be the cause of the probems we are experienging. The UART speed is set on the host to 115200 8n1. I wait for "BOOTME" (even if the first character is lost somehow so we actually received "OOTME") then I start uploading the AIS file in UART format. The problem is that we never manage to complete the upload correctly. Most of the times there is no reply from DM6435 after the upload (I suppose some bytes were lost in the upload), some other times the DM6435 replies with "CORRUPT DATA". Is there any way to enable sowftware handshking or something similar?
I've also tried to put a small delay between the sending of each character but this only made the situation worse (no reply from DSP).
Then we decide to try SPI boot. The DSP SPI port is connected to the SPI interface on a host processor (instead of EEPROM) that's acting as slave. The idea is that the host processor provides the data to the DSP. First problem: just after reset the DSP sends some 20 clocks on the SPI clock line that our host does not ignore because the CS pin is not connected. We managed to solve this, even if clock activity is strange. Then we encountered the second problem: our host is not fast enough to provide data after it decodes the address. Basically the DM6435 sends SPI read command (value 3) followed by the address and then on the following clock pulse it expects to read the correct byte. This leaves us with only 1 clock pulse time to decode the address, gather the requested byte and put it on the SPI interface. Since the address must be decoded we have no way to provide the data using some fast streaming method (I.e. DMA).
Perhaps there is some way for the DM6435 to allow the slave to send a wait state signal or something similar? If there is no way then if becomes difficult for a host processor to make the DM6435 boot using SPI.
If you have any advice for either UART or SPI boot through a host processor it would be great!
Thanks!