path: root/nfc
diff options
authorWerner Almesberger <>2015-09-09 09:39:29 -0300
committerWerner Almesberger <>2015-09-09 09:47:31 -0300
commit262f8af491b5000d70125d45b5ec9b4f28bef6a0 (patch)
treeb594d654a93112456ee660e513dc4e24f6ddfd98 /nfc
parent1beb20a77c73c66ee66bdf58bba1903ce1dcb92e (diff)
nfc/nfc.tex: SWP clarifications; add more KL16/KL26; use \iis; bump date
Diffstat (limited to 'nfc')
1 files changed, 10 insertions, 6 deletions
diff --git a/nfc/nfc.tex b/nfc/nfc.tex
index 5fdb036..ece46cb 100644
--- a/nfc/nfc.tex
+++ b/nfc/nfc.tex
@@ -38,7 +38,7 @@
\title{Neo900 NFC Subsystem \\
{\bf Draft}}
\author{Werner Almesberger}
-\date{January 5, 2015}
+\date{September 9, 2015}
@@ -1121,7 +1121,8 @@ entity that controls this interface, i.e., the modem.
However, SWP use by field-powered NFC chips, e.g., the PN544%
\footnote{Section 10.6.4 of \cite{PN544-ODS}.}, suggests that the
SWP part of a SIM is also expected to be operational without prior
-activation of the SIM.
+activation of the SIM. This is also consistent with what is shown in
+section 6.2.3 of \cite{SWP}.
\subsubsection{Role of modem}
@@ -2464,13 +2465,16 @@ in section \ref{kl26swp}. High-drive pads are marked with a grey bar.
The KL16 has no voltage regulator and no USB interface. This frees a
number of pins for use as GPIOs. In particular, this enables us to
-support two SWP interfaces.
+support two SWP interfaces for dual-SIM operation. Since both SWP
+interfaces share a single comparator, only one can transfer data at
+a time, while the other has to be held in SUSPENDED or DEACTIVATED
+state. (See section 8.3 of \cite{SWP}.)
-The dotted lines indicate connections for using I2S instead of SPI
+The dotted lines indicate connections for using \iis\ instead of SPI
for raw modes. If the pins are not used for anything else, the circuit
can connect to both sets of pins, thus leaving the choice of communication
mechanism to the firmware.
@@ -2484,13 +2488,13 @@ capacitor.
\subsection{In-circuit programming}
-The KL26's internal Flash memory can be in-circuit programmed through
+The KL16/KL26's internal Flash memory can be in-circuit programmed through
the SWD interface. To avoid conflicts with other parts of the system,
the SWD signals should either be used exclusively for SWD, or -- if
sharing is desired -- should connect to high-impedance inputs that do
not normally trigger major transitions in system state.
-Like apparently all microcontrollers of this category, the KL26 can
+Like apparently all microcontrollers of this category, the KL16/KL26 can
be programmed to disallow any direct outside access to its Flash content.
Firmware present in Flash may allow indirect read or write access to the