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Hydra Expansion Pin Out Definition — Parallax Forums

Hydra Expansion Pin Out Definition

Timothy D. SwieterTimothy D. Swieter Posts: 1,613
edited 2009-11-07 18:22 in Propeller 1
I have the Hydra book, unfortunately that is at home while I travel so it can't help me confirm what I want to know. I am working on a board for the Hydra expansion and I wanted to verify the pin out and orientation of the expansion connector. I know the pin names such as

I/O_0 to I/O_7
NET_TX_DATA
NET_RX_CLK
RESn
SCK_CART
SDA_CART
33VCC
33VCC_LOOP
5VCC
5VCC_LOOP
USB_TXD
USB_RXD
GND

From the pictures of the expansion cards I gather that one side of the card has I/O_0 to I/O_7 as well as NET_TX_DATA and NET_RX_CLK. What I need confirmation on is the pin ordering on the backside of the card. I would guess the following

I/O_0 is directly in front of GND
I/O_1 is directly in front of USB_RXD
....
NET_RX_CLK is directly in front of RESn

is this correct? I think this makes sense based on this image because I can't imagine the lines doing a flip flop across the PCB to the J2 points (if RESn was behind I/O_0). This image was helping me, but if someone has the real thing and can verify I can continue with my design. www.parallax.com/desktopmodules/catalookstore/ImageViewer.aspx?link=Images/Prod/3/323/32361-L.jpg&desc=HYDRA+128K+Memory+Expansion+Card&PortalID=0&viewerid=-1&mid=-1

Thank you.

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Timothy D. Swieter, E.I.
www.brilldea.com - Prop Blade, LED Painter, RGB LEDs, 3.0" LCD Composite video display, eProto for SunSPOT
www.tdswieter.com

Comments

  • Mike GreenMike Green Posts: 23,101
    edited 2009-05-10 15:42
    Exp pin 1 - I/O_0
    Exp pin 2 - I/O_1
    Exp pin 3 - I/O_2
    Exp pin 4 - I/O_3
    Exp pin 5 - I/O_4
    Exp pin 6 - I/O_5
    Exp pin 7 - I/O_6
    Exp pin 8 - I/O_7
    Exp pin 9 - NET_TX_DATA
    Exp pin 10 - NET_RX_DATA

    Exp pin 11 - RESn
    Exp pin 12 - SCK_CART
    Exp pin 13 - SDA_CART
    Exp pin 14 - 33VCC
    Exp pin 15 - 3VCC_LOOP
    Exp pin 16 - 5VCC
    Exp pin 17 - 5VCC_LOOP
    Exp pin 18 - USB_TXD
    Exp pin 19 - USB_RXD
    Exp pin 20 - GND

    Looking down from above, pin 1 is in the lower righthand corner, pin 10 is in the lower lefthand corner, pin 11 is in the upper lefthand corner, and pin 20 is in the upper righthand corner with the front of the expansion card facing downwards.
  • Timothy D. SwieterTimothy D. Swieter Posts: 1,613
    edited 2009-05-10 16:47
    Thank you Mike!

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    Timothy D. Swieter, E.I.
    www.brilldea.com - Prop Blade, LED Painter, RGB LEDs, 3.0" LCD Composite video display, eProto for SunSPOT
    www.tdswieter.com
  • Oldbitcollector (Jeff)Oldbitcollector (Jeff) Posts: 8,091
    edited 2009-05-16 21:20
    Silly design question perhaps. (Or I just don't completely understant it.-likely)

    Why the 5v and 3v LOOP connections? These seem redundant to me.
    If I read the specs correctly it looks like they are simply tied to their
    3V and 5V counterparts. Why call them LOOPS at all?

    Or do they serve another purpose I'm not seeing?

    OBC

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  • Timothy D. SwieterTimothy D. Swieter Posts: 1,613
    edited 2009-05-17 02:09
    I am still away from home and don't have the Hydra book in front of me, but I thought the loops had indicators or I/O connections to the Hydra to indicate a card was inserted. At a minimum one of the loops disables the EEPROM on the Hydra so the EEPROM on the card can be the active EEPROM for loading the system.

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    Timothy D. Swieter, E.I.
    www.brilldea.com - Prop Blade, LED Painter, RGB LEDs, 3.0" LCD Composite video display, eProto for SunSPOT
    www.tdswieter.com
  • WBA ConsultingWBA Consulting Posts: 2,935
    edited 2009-11-04 01:06
    I just got my Hydra back from my dad and happened to be looking at the Hydra schematic over lunch today to convert it to a development platform. I was trying to figure out the same thing about the 5v and 3.3v "loops". After a hard look at the full circuit, I discovered that when an expansion card is inserted, it changes the A1 line on the onboard EEPROM to high via the 3vcc loop line, thus changing the EEPROM's address. With the EEPROM on the expansion card set at 000, the propeller boots off of it instead. This is a slick way to safely manage expansion cards that are EEPROM/address based.

    My next challenge is figuring out why the keyboard and mouse connections are using two IO pins for each connection. (IE: the keyboard data line is taking up P13 and P14) I don't understand what's going on with the 3 resistors and 2N3904.

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    Andrew Williams
    WBA Consulting
    WBA-TH1M Sensirion SHT11 Module
    Special Olympics Polar Bear Plunge, Mar 20, 2010
  • WBA ConsultingWBA Consulting Posts: 2,935
    edited 2009-11-07 18:22
    Page 143 in the Hydra book answered my question. The dual IO pins for each line and the 3904 circuit exist to allow true-to-spec 2 way PS2 communication. I can free up 4 IO pins by eliminating the part of the circuit that allows the PS2 device to receive data from the propeller and just use the part that receives data from the PS2 device.

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    Andrew Williams
    WBA Consulting
    WBA-TH1M Sensirion SHT11 Module
    Special Olympics Polar Bear Plunge, Mar 20, 2010
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