Target Board Information STMicroelectronics STb710x Reference Board (mb442) Board version information

Several versions of the STx710x Reference board have been made, which can make identifying a board difficult. Obvious differences include whether the board has a 7100 or a 7109 (in which case additional components and a connector should be present for the on-chip Ethernet MAC). Less obvious but equally important is the board revision. We have only ever seen rev B and C boards, so its possible rev A was only a prototype.

Board version identification

Many of the early mb442 boards do not have a silk screen, and even those which do frequently don't give the board revision. If you are lucky, the board may have a sticker on it with a number like 20617053 B.07. In this case the B indicates this is a rev B board. Sometimes these stickers use digits instead of letters, so in 20605879 2-03, the 2 before the dash indicates it is a rev B. If all else fails the number of power regulators between the JTAG connector and the edge of the board can be used: rev B boards had four, rev C only have three.

Examples

mb442 rev B with STi7109 cut 2.0. Ethernet hardware populated complete with all board modifications.
Enlarge: Small (99K), Large (320K).

mb442 rev B with STx7100 cut 3.1.
Enlarge: Small (91K), Large (297K).

mb442 rev B with STx7100 cut 2.0. Note missing board modifications.
Enlarge: Small (111K), Large (371K).

mb442 rev C with STi7109 cut 3.0. Ethernet hardware populated no board modifications required.
Enlarge: Small (100K) Large (329K)

mb442 rev B

There are two issues rev B board users may need to be aware of:

• The polarity of the USB overcurrent detection pin on the 710x devices changed between silicon revisions. For 7100 versions upto and including cut 3.0 and 7109 cut 1.0 USB2_PRT_OVRCUR was active high, more recent parts are active low. The mb442 rev B has a option resistor which allows the over current signal to be selectively inverted depending on which silicon revision is being used.

  This is selected by resistor R19 which is positioned just behind the IR receiver on the front of the board (picture). This resistor has two possible positions. It should be nearer the edge of the board to select the inverted signal for early silicon, and towards the center of the board for later silicon.

• The mb442 rev B requires several modifications to support the on-chip Ethernet MAC of the 7109 (picture). Some of these are very delicate, and should be double checked if there are Ethernet problems. In particular the resistor attached directly to the STE100P sometimes shorts out with the adjacent pins, and needs to be repositioned.