Unconnected pins, board dimensions and hole positions
Added by Thomas Catalino 10 months ago
Posting on behalf of customer:
1.The J1 and J3 connectors of MitySOM-AM57 are described as “MFIO” for “Type”.
"If this pin is not used, can it be left unconnected?"
(Table 6, Table 7 in MitySOM-AM57_datasheet.pdf)
2.Is it okay to leave it unconnected even if it is not used with “ModuleFixed-FunctionPin (FF)”?
(Table 6, Table 7 in MitySOM-AM57_datasheet.pdf)
3. I read the board dimensions and hole positions of ”MitySOM-AM57” from the ODB data of ”MitySOM-AM57F-DevKit”, but there are differences from the data sheet of ”MitySOM-AM57”.
"Which is correct, the ODB data or the datasheet?"
See attached file: Dimensions read from ODB data are in red
(I think there is also an inch-mm conversion error, but the maximum is 0.3 mm.)
Replies (4)
RE: Unconnected pins, board dimensions and hole positions - Added by Michael Williamson 10 months ago
Hello.
1. Generally speaking, all of the MFIO pins are direct connects to the AM57xx CPU device and if they are unused in your design it is safe to leave them not connected. The Ball numbers are included in the table and can be cross referenced to the processor datasheet. Table 4-2 of the processor datasheet indicates the ball reset and default state. Most, if not all, pins are defaulted as high impedance (output driver disabled) with an active internal pullup resistor to the ball's respective bank voltage.
2. Of the FF pins, it is strongly recommended that you implement the PB_RESETn (at a minimum, pull it to 3.3V) and consider the AM57_BOOT_MODE pin default "high" is what you require. The other pins should be OK to leave disconnected (USB, DATA, HDMI, FPGA ADC, etc.).
For additional information about unused signals connected to the AM57xx, see section 2.5 of the AM57xx schematic checklist from TI.
If you have specific pins that are of concern, please let us know which ones.
3. Please refer to revision 1H of the datasheet, the figure you are referencing is from an older version. The datasheet figure only shows precision to 10 microns, so some of the spacings are rounded in the datasheet (which should be OK for positioning of the mounting holes and studs for the heat spreader, 10 microns is under most tolerances needed for alignment). The ODB file of course is what we have provided to our CM for the next version of the board.
RE: Unconnected pins, board dimensions and hole positions - Added by Masayoshi Furuta 10 months ago
If you have specific pins that are of concern, please let us know which ones.
Is it okay to leave the following signals open when not in use?
J1-99 (AB16)
J1-101 (D21)
J3-8 (C25)
J3-10 (F17)
Looking at the AM5728 (TI) datasheet, it states that the following pin processing is required when not in use.
AB16: GND through an external pull resistor
D21, F17, C25: power supply through an external pull resistor
RE: Unconnected pins, board dimensions and hole positions - Added by Michael Williamson 10 months ago
Hello,
To be clear, this information is for the MitySOM-AM57 (non-FPGA variant). I am sorry I was thinking you were referring to the FPGA variant of the MitySOM-AM57F.
For the pins in question:
J1-99 (AB16) - the SOM includes a 1.1K pull down to ground on this net. It is OK to leave unconnected.
J1-101 (D21) - The SOM does not include any pull up resistor for this net. This should be pulled high as per the AM5728 datasheet if NMI will be enabled/used.
J3-8 (C25) - This SOM includes a 20K pull up resistor to 1.8V. It is OK to leave unconnected.
J3-10 (F17) - This SOM includes a 20K pull up resistor to 1.8V. It is OK to leave unconnected.
With regards,
Mike
RE: Unconnected pins, board dimensions and hole positions - Added by Masayoshi Furuta 9 months ago
1.The J1 and J3 connectors of "MitySOM-AM57 (non-FPGA variant)" are described as “MFIO” for “Type”.
"If this pin is not used, can it be left unconnected?"
(Table 6, Table 7 in MitySOM-AM57_datasheet.pdf)
2.The J1 and J3 connectors of "MitySOM-AM57 (non-FPGA variant)" are described as “FF” for “Type”.
"If this pin is not used, can it be left unconnected?"
(Table 6, Table 7 in MitySOM-AM57_datasheet.pdf)
3.J1 and J3 connectors of "MitySOM-AM57 (non-FPGA version)" are for pins other than "MFIO", "FF", "PWR", and "GND"
Please let me know which pins need to be connected and how to connect (PullUp, etc.).
