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Texas Instruments TNETX3270 SDRAM-type and quantity indication, initialization, refresh

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TNETX3270

ThunderSWITCH 24/3 ETHERNET SWITCH

WITH 24 10-MBIT/S PORTS AND 3 10-/100-MBIT/S PORTS

SPWS043B – NOVEMBER 1997 – REVISED APRIL 1999

38 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265

SDRAM-type and quantity indication

Before beginning operation (by writing to the start bit of Syscontrol), it is necessary to indicate to the SDRAM

interface whether × 8 or × 16 SDRAMs are being used. This is done by setting the bit in the RAMsize register

(by 8 = 0 for × 16, by 8 = 1 for × 8) during the load from EEPROM or via a DIO write. It also is necessary to inform

the SDRAM interface of the quantity of external SDRAM available. This is done by writing to the RAMsize

register, while at the same time setting the × 8 or × 16 SDRAMs.

initialization

SDRAMs require controlled initialization. Specifically, SDRAMs require up to 200 µs of inactivity after power has

been supplied, during which they are supplied only with an active CLK. The system designer must ensure that

this inactivity period is observed while TNETX3270 is held in hardware or software reset.

Table 17 shows the state of the SDRAM interface terminals during hardware or software reset.

Table 17. SDRAM Interface Terminal State During Hardware or Software Reset

TNETX3270

TERMINAL STATE

DURING RESET

DA13–DA00 Driven high

DRAS Driven high

DCAS Driven high

DW Driven high

DCLK Active

DD31–DD00 High impedance

Any other SDRAM requirements during this period that need to be observed, such as the state of chip selects

and clock-enable and data-mask controls, also are the responsibility of the system designer. This SDRAM

interface does not drive the DD bus during hardware or software reset, or following either reset, until the SDRAM

initialization process has been completed.

refresh

After the initialization process, the SDRAM interface then performs 4096 REFR commands at least every 64 ms.

SDRAM data is, however, lost during any subsequent resets, as the SDRAM interface does not issue any REFR

commands during any hardware or software reset.

Contents

Main TNETX3270 ThunderSWITCH24/3 ETHERNET SWITCH WITH 24 10-MBIT/S PORTS AND 3 10-/100-MBIT/S PORTS TNETX3270 ThunderSWITCH24/3 ETHERNET SWITCH WITH 24 10-MBIT/S PORTS AND 3 10-/100-MBIT/S PORTS description TNETX3270 ThunderSWITCH24/3 ETHERNET SWITCH WITH 24 10-MBIT/S PORTS AND 3 10-/100-MBIT/S PORTS ThunderSWITCH24/3 ETHERNET SWITCH WITH 24 10-MBIT/S PORTS AND 3 10-/100-MBIT/S PORTS SPWS043B NOVEMBER 1997 REVISED APRIL 1999 PGV PACKAGE (TOP VIEW) ThunderSWITCH 24/3 ETHERNET SWITCH PRODUCT PREVIEW Figure 1. TNETX3270 Interface Block Diagram Page TNETX3270 10-/100-Mbit/s MAC interface (ports 2426) 10-/100-Mbit/s MAC interface (ports 2426) (continued) SDRAM interface WITH 24 10-MBIT/S PORTS AND 3 10-/100-MBIT/S PORTS host DIO interface serial MII management PHY interface EEPROM interface LED interface JTAG interface miscellaneous power interface summary of signal terminals by signal group function DIO register groups Table 1. Internal Register and Statistics Memory Map Table 2. Detailed DIO Register Map Page Page Page interface description receiving/transmitting management frames state of DIO signals during hardware reset network management port Page Page receive control giant (long) frames short frames receive filtering of frames data transmission transmit control adaptive performance optimization (APO) (transmit pacing) interframe gap enforcement ThunderSWITCH 24/3 ETHERNET SWITCH WITH 24 10-MBIT/S PORTS AND 3 10-/100-MBIT/S PORTS receive versus transmit priority uplink pretagging Table 5. Source-Port Pretag Encoding Page TNETX3270 interaction of EEPROM load with the SIO register summary of EEPROM load outcomes compatibility with future device revisions HIGHZ instruction lamp test multi-LED display hardware configurations Page TNETX3270 Figure 6. 10-Mbit/s Interface-Port Signal Timing Figure 7. Connecting to TNETE2008 PHY 10-/100-Mbit/s port configuration 10-/100-Mbit/s port configuration (continued) 10-/100-Mbit/s port configuration in a nonmanaged switch 10-/100-Mbit/s port configuration in a managed switch SDRAM interface (continued) Table 15. TNETX3270 Terminal Interface to SDRAMs SDRAM-type and quantity indication initialization refresh 39 frame routing txacc Figure 8. VLAN Overview Transmit rxacc IEEE Std 802.1Q headers reception IEEE Std 802.1Q headers transmission address maintenance spanning-tree support aging algorithms frame-routing determination Unkmem Figure 9. Frame-Routing Algorithm interrupt UnkVLAN Figure 9. Frame-Routing Algorithm (Continued) new chng secvio Port Trunking/Load Sharing port mirroring port trunking/load sharing collision-based flow control IEEE Std 802.3 flow control Page internal wrap test duplex wrap test Page absolute maximum ratings over operating junction temperature range (unless otherwise noted) recommended operating conditions electrical characteristics over recommended operating conditions (unless otherwise noted) PARAMETER MEASUREMENT INFORMATION test measurement 10-Mbit/s interface (ports 0023) timing requirements (see Notes 3 through 6 and Figure 13) Figure 13. 10-Mbit/s Interface (Ports 0023) 10-/100-Mbit/s MAC interface Figure 14. 10-/100-Mbit/s Receive Ports 10-/100-Mbit/s timing requirements (see Note 7 and Figure 14) 10-/100-Mbit/s timing requirements (see Figure 15) operating characteristics over recommended operating conditions (see Note 8 and Figure 15) Figure 15. 10-/100-Mbit/s Transmit Ports SDRAM interface SDRAM subcycle operating characteristics over recommended operating conditions (see Figure 17) Figure 17. SDRAM Subcycle DIO/DMA interface Figure 18. DIO/DMA Write Cycle timing requirements (see Figure 18) operating characteristics over recommended operating conditions (see Figure 18) DIO/DMA read cycle timing requirements (see Figure 19) Figure 19. DIO/DMA Read Cycle operating characteristics over recommended operating conditions (see Figure 19) serial MII management interface timing requirements (see Figure 20) operating characteristics over recommended operating conditions (see Figure 20) Figure 20. Serial MII Management Read/Write Cycle EEPROM interface operating characteristics over recommended operating conditions (see Figure 21) Figure 21. EEPROM LED interface operating characteristics over recommended operating conditions (see Figure 22) Figure 22. LED power-up OSCIN and RESET timing requirements (see Figure 23) Figure 23. Power-Up OSCIN and RESET MECHANICAL DATA PGV (S-PQFP-G240) PLASTIC QUAD FLATPACK (DIEDOWN)