Shmoo Tests
Shmoo tab contains a suite of tests designed to experiment with different
Initial Board Setting values and display a map of the results. The list of possible
values depends on the currently selected memory type, but all memory types offer the
following Shmoo tests:
-
Write Test – PHY Drive Strength and DRAM ODT are varied across the list
of possible values. Consecutive trainings are executed, displaying the results
for each combination of values.
Figure 1. Write test results 
- Read Test – PHY ODT and DRAM Drive Strength are varied across the list of
possible values. Consecutive trainings are executed, displaying results for each
combination of values.
Figure 2. Read test results 
- Phy Vref – the purpose of this test is to get an optimized Phy Vref value
which will be used as starting value for the consequent 1D trainings. This is
useful when the default value provided for Phy Vref is not good enough for the
custom board to have 1D training passing because if 1D training is already
passing, Phy Vref is further optimized during 2D training. The test will display
as result the value of Phy Vref Quotient corresponding to the optimized Vref
value.
Figure 3. Phy Vref test results 
Note: Although the parameter values are modified during the shmoo process, the initial
DDR configuration is restored once the test finishes. To apply a given
configuration, use the context menu from Test Results table, available for all cells
which have valid configurations (training passed).
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Once the configuration is updated, DDR View will reflect the changes and a new training can be executed with the current configuration.