Monday, May 4, 2015

Short but unproductive day chasing problems in the SAC Interface Box


Testing virtual 2501 card reader

I worked on the logic and found I was not getting the initial DSW set up properly. I still think this problem stems from lack of synchronization between the status process that updates 1130 machine states on the GUI and the virtual device driver  use of the USB link. This seems to get the link out of sync right at the times when the virtual 2501 is switching between Ready and Not Ready state. That is how my status process determines it should not be using the USB link.

A simple test will verify if this is factor in the problem - simply by disabling the status update process entirely, leaving the virtual device adapter as the only communicating entity. I ran the test and the problem still exists. I have to fall back and instrument the transactional sequences to make sure I am receiving them properly and that they are doing what they should.

I am facing a very strange situation - Some of the transaction codes work properly, others don't, yet they are very parallel in construction. Worse, I have a one time triggered latch to tell me if the transaction engine saw the code, but it isn't firing. Yet, other lights are showing the code. I am not sure what is happening here but at least once I find it I expect it to be the root of all the little issues remainoing.

High speed SPI link testing

I finished up the data pump code in the slave board and the temporary testing fixtures using switches, buttons and lights on that board. I connected the boards and did not see my messages echoed, so on to the next level of debugging. To ease the conditions, I further slowed the link to 100KHz which should eliminate signal quality issues and leave me focused purely on the logic of my use. .

Still nothing and my scope is not seeing any attempts to clock the slave. I have to look into the data pump logic itself in the master, instrumenting and verifying if it is working. 

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