--
Uwe Bonnes bon@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Institut fuer Kernphysik Schlossgartenstrasse 9 64289 Darmstadt
--------- Tel. 06151 162516 -------- Fax. 06151 164321 ----------
>From a5afb810b204b911c524106acee32b04dfd1791f Mon Sep 17 00:00:00 2001
From: Uwe Bonnes <bon@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>
Date: Tue, 6 Sep 2011 10:39:48 +0200
Subject: Explain the index/value format baudrate setting
test/baudrate.cpp: Evaluate according to this explanation
---
src/ftdi.c | 12 ++++++++++++
test/baudrate.cpp | 22 ++++++++++++++++++----
2 files changed, 30 insertions(+), 4 deletions(-)
diff --git a/src/ftdi.c b/src/ftdi.c
index 66c159e..0c8d540 100644
--- a/src/ftdi.c
+++ b/src/ftdi.c
@@ -1069,6 +1069,18 @@ static int ftdi_to_clkbits_AM(int baudrate, unsigned
long *encoded_divisor)
clk/2 -> 2
From /2, 0.125 steps may be taken.
The fractional part has frac_code encoding
+
+ value[13:0] of value is the divisor
+ index[9] mean 12 MHz Base(120 MHz/10) rate versus 3 MHz (48 MHz/16) else
+
+ H Type have all features above with
+ {index[8],value[15:14]} is the encoded subdivisor
+
+ FT232R, FT2232 and FT232BM have no option for 12 MHz and with
+ {index[0],value[15:14]} is the encoded subdivisor
+
+ AM Type chips have only four fractional subdivisors at value[15:14]
+ for subdivisors 0, 0.5, 0.25, 0.125
*/
static int ftdi_to_clkbits(int baudrate, unsigned int clk, int clk_div,
unsigned long *encoded_divisor)
{
diff --git a/test/baudrate.cpp b/test/baudrate.cpp
index 0d2e0b8..7ce2e9a 100644
--- a/test/baudrate.cpp
+++ b/test/baudrate.cpp
@@ -87,10 +87,24 @@ static void test_baudrates(ftdi_context *ftdi, const
map<int, calc_result> &baud
const calc_result *res = &baudrate.second;
- unsigned short divisor = calc_value & 0x3ff;
- unsigned short fractional_bits = (calc_index & 0x100) ? 4 :
(calc_value >> 12);
- unsigned short clock = (calc_index & 0x100) ? 120 : 48;
-
+ unsigned short divisor = calc_value & 0x3fff;
+ unsigned short fractional_bits = (calc_value >> 14);
+ unsigned short clock = (calc_index & 0x200) ? 120 : 48;
+
+ switch (ftdi->type)
+ {
+ case TYPE_232H:
+ case TYPE_2232H:
+ case TYPE_4232H:
+ fractional_bits |= (calc_index & 0x100) ? 4 : 0;
+ break;
+ case TYPE_R:
+ case TYPE_2232C:
+ case TYPE_BM:
+ fractional_bits |= (calc_index & 0x001) ? 4 : 0;
+ break;
+ default:;
+ }
// Aid debugging since this test is a generic function
BOOST_CHECK_MESSAGE(res->actual_baudrate == calc_baudrate &&
res->divisor == divisor && res->fractional_bits == fractional_bits
&& res->clock == clock,
--
1.7.3.4
--
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