UM10741
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© NXP B.V. 2014. All rights reserved.
User manual
Rev. 1 — 1 April 2014
14 of 61
NXP Semiconductors
UM10741
Fm+ development kit OM13320
Each bus has a GPIO 8-bit Slave device (PCA9672, IC10 and IC20), and Bus 1 also has
an LED Driver 16-channel device (PCA9955, IC6). All sixteen outputs are connected to
LEDs, for visual indication. The 8-bit GPIOs require connection of GPIO Target Boards
(OM13303, supplied in the kit) to both indicate the output using eight LEDs and allow user
input from eight push switches.
An NXP LPC1343 Microcontroller (MCU) serves as both the Bus 1 Master, and the USB
link. The firmware on the MCU can be replaced by the In-System Programming (ISP)
mode, with data sent over the USB link (CN5).
Bus 2 has a Parallel to I
2
C-bus Controller device (PCA9665, IC6), which is to be driven by
an optional NXP LPC Xpresso module (not supplied). That module is also an I
2
C Master
and connected to Bus 2.
Remark:
Although Bus 2 has more than one I
2
C Master, only one is active at any time.
The remaining circuitry is to support the I
2
C devices, and provide communications with the
PC over a USB link.
The main operating voltage on the Fm+ Development Board (OM13260) is 3.3 V supplied
from a linear regulator (IC1). Some circuits and the optional I
2
C-bus pull-ups may run from
5 V derived either from the USB host (typically a PC) or an AC-DC power supply (not
supplied in the kit). The actual voltage is seldom 5 V, due to cable losses, plus an
additional drop in a series connected diode used to OR the two inputs. Whichever has the
highest voltage has priority.
A shunt Zener diode (6.2 V) protects the board from reverse polarity and overvoltage at
the DC Power connector (CN6).
To aid in understanding digital signal levels on the board, two ‘logic probe’ circuits are
provided. These are buffered LEDs (Green, D6 and Red, D7), which light if their
respective inputs (CN11) are grounded.
Two global digital signal nets, called INT (interrupt) and RST (reset) connect all I
2
C-bus
devices on the board and also the Port A – Port E Daughter Card connectors. These are
also connected to the Master (MCU, IC5) on Bus 1, the Master (Bus Controller, IC4), and
the LPC Xpresso module.
Remark:
The I
2
C global Reset is not the same as the MCU Reset. Resetting the MCU will
only reset the I
2
C-bus if the MCU firmware is intended to create a global reset.
The test points provide monitoring of interrupts (usually generated by I
2
C-bus Slaves) and
software reset of Fm+ class I
2
C-bus devices that have that feature.
Additional buffered LEDs are provided (D19, RST and D20, Interrupt) on the Fm+
Development Board (OM13260) for visual indication.
Various MCU and LPC Xpresso signals are made available through additional connectors.
These include a serial Port (CN7) with EIA232 voltage level translation (IC2) and SPI Bus
signals (SP0, CN9 and SP1, CN8) from the LPC Xpresso module, together with SPI Bus
(SP2, CN16) from the MCU (IC5).
A prototyping area is provided for solder connection of components that may be required
by an application circuit beyond this board’s design. Power supplies and other signals are
readily available.
