DS90UB949-Q1: How to connect for unused GPIO??

Harry Shin1

Expert 6790 points

Part Number: DS90UB949-Q1

Hello team,

While I checked my customer schematic for 949, I see no connection for unused pins as below table.

But I don't have any guide from datasheet if they can be leave as floating.

Could you pls help check it??

PIN		I/O, TYPE	DESCRIPTION	DES 940	SER 949 connection
NAME	NO.	I/O, TYPE	DESCRIPTION	DES 940	SER 949 connection
D_GPIO0 / MOSI	8	IO, LVCMOS IO, LVCMOS	HS GPIO0. Shared with MOSI SPI Master Out Slave In. Shared with D_GPIO0	not use	??
D_GPIO1 MISO	10	IO, LVCMOS IO, LVCMOS	HS GPIO1. Shared with MISO SPI Master In Slave Out. Shared with D_GPIO1	not use	??
D_GPIO2 SPLK	11	IO, LVCMOS IO, LVCMOS	HS GPIO2. Shared with SPLK SPI Clock. Shared with D_GPIO2	not use	??
D_GPIO3 SS	12	IO, LVCMOS IO, LVCMOS	HS GPIO3. Shared with SS SPI Slave Select. Shared with D_GPIO3	not use	??
SDIN / GPIO0	4	I, LVCMOS IO, LVCMOS	Master Mode I2S Data Input. Shared with GPIO0 BCC GPIO0. Shared with SDIN	not use	??
SWC / GPIO1	5	O, LVCMOS IO, LVCMOS	Master Mode I2S Word Clock Output. Shared with GPIO1 BCC GPIO1. Shared with SWC	not use	??
I2S_DC GPIO2	37	I, LVCMOS IO, LVCMOS	Slave Mode I2S Data Input. Shared with GPIO2 BCC GPIO2. Shared with I2S_DC	not use	??
I2S_DD GPIO3	38	I, LVCMOS IO, LVCMOS	Slave Mode I2S Data Input. Shared with GPIO3 BCC GPIO3. Shared with I2S_DD	not use	??
I2S_DB GPIO5_REG	36	I, LVCMOS IO, LVCMOS	Slave Mode I2S Data Input. Shared with GPIO5_REG General-Purpose Input/Output 5 Local register control only. Shared with I2S_DB	not use	??
I2S_DA GPIO6_REG	35	I, LVCMOS IO, LVCMOS	Slave Mode I2S Data Input. Shared with GPIO6_REG General-Purpose Input/Output 6 Local register control only. Shared with I2S_DA	not use	??
I2S_WC GPIO7_REG	33	I, LVCMOS IO, LVCMOS	Slave Mode I2S Word Clock Input. Shared with GPIO7_REG General-Purpose Input/Output 7 Local register control only. Shared with I2S_WC	not use	??
I2S_CLK GPIO8_REG	34	I, LVCMOS IO, LVCMOS	Slave Mode I2S Clock Input. Shared with GPIO8_REG General-Purpose Input/Output 8 Local register control only. Shared with I2S_CLK	not use	??
MCLK	16	IO, LVCMOS	Master Mode I2S System Clock Input/Output	not use	??

Thank you.

over 2 years ago

0 Clemens Ladisch over 2 years ago

Guru 317350 points

Unused outputs can be left open. Unused inputs must not float; if there are no internal pull-up or pull-down resistors, you should add external ones.

How are the pins configured? As far as I can see, the default setting is for the function, not GPIO.

+1 Kate Hawkins over 2 years ago

TI__Intellectual 2830 points

Hi Harry,

As long as the unused pins are functionally off, you can either leave them unconnected or tie to weak pulldowns which may help improve EMC performance. A value like 10k should be sufficient if needed.

Thanks,
Kate

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DS90UB949-Q1: How to connect for unused GPIO??