KS8695X 74LS174 M9999-050604 - Datasheet Archive

 

Micrel Application Note 108 Supporting Extra LEDs with the KS8695X 5-Port Integrated High Performance Gateway KS8695X General

 

Application Note 108 Micrel Application Note 108 Supporting Extra LEDs with the KS8695X KS8695X 5-Port Integrated High Performance Gateway KS8695X KS8695X General Description VCC VCC VCC VCC VCC If an extra LED is needed to support legacy implementations, there are two possible solutions. The first solution uses a single GPIO per port as the speed LED indicator. The second solution uses two GPIOs plus an external chip to provide a third LED indicator per Ethernet port. Although this solution requires an external chip, it uses a minimal number of GPIOs to provide a third LED indicator per Ethernet port. Figure 1 shows the hardware connection for this solution. KS8695X KS8695X GPIOA D SET CLR GPIOB D WRSTO SET CLR D LED Information SET CLR The KS8695X KS8695X has two LED indicators per Ethernet port. Each of these LED indicators can be configured to indicate the following: Speed, Link, Full duplex, Collision, Activity, Full duplex/Collision, or Link/Activity. The LAN LEDs are configured in the KS8695X KS8695X Switch Engine Control Register at offset 0xE800. Bits 27:25 control LANxLED1 and bits 24:22 control LANxLED0. The WAN LEDs are configured in the KS8695X KS8695X WAN Miscellaneous Control Register at offset 0xEA0C. Bits 6:4 control WAN LED1 and bits 2:0 control WAN LED0. The programming values are given in Table 1. Bits LED Indicator Speed Link Full Duplex Collision Activity Full Duplex/Collision On/Blink 110 Link/Activity On/Blink 111 Disabled Q Q LAN1 Speed LED Q Q LAN2 Speed LED Q Q LAN3 Speed LED Q Q LAN4 Speed LED To implement this solution, use a 74LS174 74LS174 or similar IC. The 74LS174 74LS174 contains six D-type flip-flops; however, only five Dtype flip-flops are shown in the Figure 1. Software to read the connection speed of each port of the port registers also needs to be written. This code generates a serial data stream consisting of each port's link speed on GPIOA. The software also toggles the state of GPIOB, which serves as the clock signal. By toggling GPIOB as the clock signal, the software shifts the serial data on GPIOA into the appropriate registers to indicate the speed for each port. Figure 2 shows a timing diagram that illustrates how port speed data is shifted into the registers. Blink 101 WAN Speed LED Implementation Blink 100 Q Figure 1. LED Support Using Minimum GPIO On 011 SET CLR On 010 D On 001 SET CLR LED State 000 D Q Off GPIOA (Data) LAN4 Spd LAN3 Spd LAN2 Spd LAN1 Spd WAN Spd Table 1. Bit Programming Values for LEDs GPIOB (Clock) Figure 2. Serial Shift Speed Data Timing Diagram Advantage and Disadvantage of the Second Solution The reset input on the 74LS174 74LS174 is connected to the KS8695X KS8695X reset output WRSTO. This ensures that the 74LS174 74LS174 comes up in a known state at reset time, before any programming of the registers is done. This cost effective solution provides an effortless means to support three LEDs per port. The advantage of the second solution is that it uses a minimum number of GPIOs to provide a third LED indicator per Ethernet port. Figure 1 shows the hardware connection for the second option. The disadvantage is that it requires an external integrated circuit (IC). For additional support, contact your local Micrel Field Application Engineer or salesperson. Micrel, Inc. · 1849 Fortune Drive · San Jose, CA 95131 · USA · tel + 1 (408) 944-0800 · fax + 1 (408) 474-1000 · http://www.micrel.com May 2004 1 M9999-050604 M9999-050604 Application Note 108 Micrel MICREL, INC. 1849 FORTUNE DRIVE TEL + 1 (408) 944-0800 FAX SAN JOSE, CA 95131 + 1 (408) 474-1000 WEB USA http://www.micrel.com The information furnished by Micrel in this data sheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel for its use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer. Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A Purchaser's use or sale of Micrel Products for use in life support appliances, devices or systems is at Purchaser's own risk and Purchaser agrees to fully indemnify Micrel for any damages resulting from such use or sale. © 2004 Micrel, Incorporated M9999-050604 M9999-050604 2 May 2004