stm32f2xxx: comments about frequency choice

[fw/openocd] / tcl / target / stm32f2xxx.cfg

diff --git a/tcl/target/stm32f2xxx.cfg b/tcl/target/stm32f2xxx.cfg
index 9ebc00f34a86c1b71e4de11f03ca77592e628840..8a85724409650ff9fd5ec67de98b3b1528f7fec2 100644 (file)
--- a/tcl/target/stm32f2xxx.cfg
+++ b/tcl/target/stm32f2xxx.cfg
@@ -21,6 +21,11 @@ if { [info exists WORKAREASIZE] } {
 }
 
 # JTAG speed should be <= F_CPU/6. F_CPU after reset is 8MHz, so use F_JTAG = 1MHz
+#
+# Since we may be running of an RC oscilator, we crank down the speed a
+# bit more to be on the safe side. Perhaps superstition, but if are
+# running off a crystal, we can run closer to the limit. Note
+# that there can be a pretty wide band where things are more or less stable.
 jtag_khz 1000
 
 jtag_nsrst_delay 100