From: Marek Vasut <redacted>
Date: Sun, 20 Apr 2014 14:53:13 +0000 (+0200)
Subject: asix-sigma: Document sampling rate table
X-Git-Tag: libsigrok-0.3.0~54
X-Git-Url: http://sigrok.org/gitweb/?a=commitdiff_plain;h=b1648dea88d378d814bc7168c1ad6247677f65cc;p=libsigrok.git

asix-sigma: Document sampling rate table

Add comments to the sampling rate table explaining how the frequencies
are selected and where do those numbers come from.

Signed-off-by: Marek Vasut <redacted>
---

diff --git a/hardware/asix-sigma/asix-sigma.c b/hardware/asix-sigma/asix-sigma.c
index 1c8e04bd..d17558d4 100644
--- a/hardware/asix-sigma/asix-sigma.c
+++ b/hardware/asix-sigma/asix-sigma.c
@@ -43,17 +43,23 @@ SR_PRIV struct sr_dev_driver asix_sigma_driver_info;
 static struct sr_dev_driver *di = &asix_sigma_driver_info;
 static int dev_acquisition_stop(struct sr_dev_inst *sdi, void *cb_data);
 
+/*
+ * The ASIX Sigma supports arbitrary integer frequency divider in
+ * the 50MHz mode. The divider is in range 1...256 , allowing for
+ * very precise sampling rate selection. This driver supports only
+ * a subset of the sampling rates.
+ */
 static const uint64_t samplerates[] = {
-	SR_KHZ(200),
-	SR_KHZ(250),
-	SR_KHZ(500),
-	SR_MHZ(1),
-	SR_MHZ(5),
-	SR_MHZ(10),
-	SR_MHZ(25),
-	SR_MHZ(50),
-	SR_MHZ(100),
-	SR_MHZ(200),
+	SR_KHZ(200),	/* div=250 */
+	SR_KHZ(250),	/* div=200 */
+	SR_KHZ(500),	/* div=100 */
+	SR_MHZ(1),	/* div=50  */
+	SR_MHZ(5),	/* div=10  */
+	SR_MHZ(10),	/* div=5   */
+	SR_MHZ(25),	/* div=2   */
+	SR_MHZ(50),	/* div=1   */
+	SR_MHZ(100),	/* Special FW needed */
+	SR_MHZ(200),	/* Special FW needed */
 };
 
 /*