u-blox SARA-R4 Series System Integration Manual

Contents

SARA-R4 series - System Integration ManualUBX-16029218 - R06 Design-inPage 71 of 1022.6.3 SPI interface2.6.3.1 Guidelines for SPI circuit designThe SPI interface is not supported by “00”, “01” and “02” product versions: the SPI interface pins shouldnot be driven by any external device.2.6.4 SDIO interface2.6.4.1 Guidelines for SDIO circuit designThe SDIO interface is not supported by “00”, “01” and “02” product versions: the SDIO interface pinsshould not be driven by any external device.2.6.5 DDC (I2C) interface2.6.5.1 Guidelines for DDC (I2C) circuit designDDC (I2C) interface is not supported by “00” and “01” product versions: the DDC (I2C) interface pinsshould not be driven by any external device.The DDC I2C-bus master interface can be used to communicate with u-blox GNSS receivers and other externalI2C-bus slaves as an audio codec.The SDA and SCL pins of the module are open drain output as per I2C bus specifications [9], and they haveinternal pull-up resistors to the V_INT 1.8 V supply rail of the module, so there is no need of additionalcomponents on the external application board.Capacitance and series resistance must be limited on the bus to match the I2C specifications (1.0 μs is themaximum allowed rise time on the SCL and SDA lines): route connections as short as possible.ESD sensitivity rating of the DDC (I2C) pins is 1 kV (Human Body Model according to JESD22-A114).Higher protection level could be required if the lines are externally accessible and it can be achieved bymounting an ESD protection (e.g. EPCOS CA05P4S14THSG varistor array) close to accessible points.If the pins are not used as DDC bus interface, they can be left unconnected.Reference Description Part Number - ManufacturerR1 47 kΩ Resistor 0402 5% 0.1 W RC0402JR-0747KL - Yageo PhycompU1 Voltage Regulator for GNSS receiver See GNSS receiver Hardware Integration Manual2.7 Audio2.7.1.1 Guidelines for Audio circuit designAudio is not supported by “00”, “01” and “02” product versions: the I2S interface pins should not bedriven by any external device.