NXP Semiconductors OM13260, Installation Manual, Page: 20 / 71

NXP Semiconductors
UMxxxxx
Install Guide
All information provided in this document is subject to legal disclaimers.
Preliminary 1
— September 6, 2013
© NXP B.V. 2013. All rights reserved.
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sixteen channel device (PCA9955, IC6). All sixteen outputs are connected to LEDs, for visual indication.
The eight 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 I2C Bus Controller device (PCA9665, IC6), which is to be driven by an optional
NXP LPC Xpresso module (not supplied). That Module is also an I2C Master and connected to Bus2.
Note: Although the Bus2 has more than one I2C Master only one is active at any time.
The remaining circuitry is to support the I2C devices, and provide communications with the PC over a
USB link.
The main operating voltage on the Fm+ Development Board (OM13260) is 3.3V supplied from a linear
regulator (IC1). Some circuits and the optional I2C Bus pull ups may run from 5V 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 five volts, 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 (6.2V) protects the board from reverse polarity and over voltage 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 I2C 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.
Note: The I2C global Reset is not the same as the MCU Reset. Resetting the MCU will only reset the
I2C Bus if the MCU Firmware is intended to create a global reset.
The test points provide monitoring of Interrupts (usually generated by I2C Slaves) and software reset of
Fm+ class I2C 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.
On the Fm+ Development Board (OM13260) V3.0 there is an LED Blinker device (PCA9901, IC3) and LED
indicator (D10), while not strictly an I2C device, as it uses a one wire protocol, it belongs to the NXP I2C