From 678ee067c4752cb0db6d69f84366f74d88614fb3 Mon Sep 17 00:00:00 2001
From: Joseph Coffland <joseph@cauldrondevelopment.com>
Date: Mon, 12 Mar 2018 03:55:51 -0700
Subject: [PATCH] Wait for pending DMA transfter to avoid missing step counts

---
 CHANGELOG.md        | 1 +
 src/avr/src/motor.c | 4 ++--
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8314278..239fbdb 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,7 @@ Buildbotics CNC Controller Firmware Change Log
  - Added site favicon.
  - Fixed problems with offsets and imperial units.
  - Fixed ``All zero s-curve times`` caused by extreemly short, non-zero moves.
+ - Fixed position drift.
 
 ## v0.3.18
  - Don't enable any tool by default.
diff --git a/src/avr/src/motor.c b/src/avr/src/motor.c
index b82a583..cf6e8a7 100644
--- a/src/avr/src/motor.c
+++ b/src/avr/src/motor.c
@@ -242,8 +242,8 @@ void motor_end_move(int motor) {
   // Stop clock
   m->timer->CTRLA = 0;
 
-  // TODO Wait for pending DMA transfers
-  //while (m->dma->CTRLB & (DMA_CH_CHBUSY_bm | DMA_CH_CHPEND_bm)) continue;
+  // Wait for pending DMA transfers
+  while (m->dma->CTRLB & DMA_CH_CHPEND_bm) continue;
 
   // Get actual step count from DMA channel
   const int24_t half_steps = 0xffff - m->dma->TRFCNT;
-- 
2.27.0