From 2d7d2d10a98f3773db6428235d86408ddb48a33d Mon Sep 17 00:00:00 2001
From: Nathan Ringo <nathan@remexre.com>
Date: Thu, 24 Oct 2024 17:15:10 -0500
Subject: rename bit

---
 fpga/src/I2C.bs | 26 ++++++++++++++++----------
 1 file changed, 16 insertions(+), 10 deletions(-)

(limited to 'fpga/src')

diff --git a/fpga/src/I2C.bs b/fpga/src/I2C.bs
index 4a302dd..292691b 100644
--- a/fpga/src/I2C.bs
+++ b/fpga/src/I2C.bs
@@ -5,15 +5,21 @@ import Clocks
 import GetPut
 
 struct I2CStatus =
-  { -- | Whether a read or write is not in progress, so a new command can be
-    -- performed. Writing this bit to move it from high to low begins a
-    -- command.
-    notBusy :: Bool
-  ; -- | Whether the bus is idle. Usually, software will want to use the
-    -- `notBusy` bit instead to determine when to send new commands; the
-    -- `busIdle` bit is only set to `True` after the STOP condition (i.e.,
-    -- after the transaction ends). Writing to this bit does not affect the
-    -- internal state of the I²C controller.
+  { -- | This bit is low when a message is being sent, and gets raised after:
+    --
+    -- - We finished sending an address, but a NACK was received.
+    -- - We finished reading a byte, including sending an ACK or NACK bit.
+    -- - We finished writing a byte, including reading an ACK or NACK bit.
+    --
+    -- When this bit is `True`, writing to it will cause a new read or write,
+    -- either in the current transaction (if this happened before `busIdle` was
+    -- lowered) or in a new one.
+    ready :: Bool
+  ; -- | Whether the bus is idle. Usually, software will want to enable
+    -- interrupts on the `ready` bit instead to determine when to send new
+    -- commands; the `busIdle` bit is only set to `True` after the STOP
+    -- condition (i.e., after the transaction ends). Writing to this bit does
+    -- not affect the internal state of the I²C controller.
     busIdle :: Bool
   ; -- | The last ACK bit we received from sending an address. Writing to this
     -- bit does not affect the internal state of the I²C controller.
@@ -107,7 +113,7 @@ mkI2C' rxSCL rxSDA txSCL txSDA addrReg dataReg statusReg = module
       txSDA := 1
     "triggered from Idle": when Idle <- state, not statusReg.notBusy ==>
       if rxSDA == 0 then do
-        statusReg := statusReg { arbitrationLost = True }
+        statusReg := statusReg { ready = True; busIdle = True; arbitrationLost = True }
         state := Idle
         txSCL := 1
         txSDA := 1
-- 
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