Adding implemenatation notes that explains the different models for simulation and synthesis of the entropy sources.

1 files changed, 13 insertions, 4 deletions

diff --git a/README.md b/README.md
index 9446500..117a972 100644
--- a/README.md
+++ b/README.md
@@ -31,7 +31,7 @@ Engineering.
 The TRNG consists of a chain with three main subsystems
 
 * Entropy generation
-* Entropy accumulation (mixer)
+* Entropy mixing
 * Random generation
 
 
@@ -74,10 +74,10 @@ before providing it as 32-bit values to the entropy accumulator.
 
 
 
-### Entropy accumulation ###
+### Entropy mixing ###
 
-The entropy acculumation subsystems reads 32-bit words from the entropy
-generators.
+The entropy mixer subsystems reads 32-bit words from the entropy
+generators to build a block of bits to be mixed.
 
 When 1024 bits of mixed entropy has been collected the entropy is used
 as a message block which is fed into a hash function.
@@ -135,6 +135,15 @@ other entropy source(s) to be connected on external ports. It is up to
 the user/system implementer to provide physical entropy souces. We will
 suggest and provide info on how to design at least one such source.
 
+For simulation there are simplistic fake entropy sources that can be
+found in the tb/fake_modules directory. This modules SHOULD NOT be used
+as real sources.
+
+For synthesis there are wrappers for the real entropy source cores to
+adapt their interfaces to what we need in the trng. These wrappers
+should not be included during simulation.
+
+
 
 ## API ##