August 2003 17 KS8737
KS8737 Micrel
Mode Selection for Register 1fh 4:2
KS8737 can be forced into a specific mode on reset by configuring MODE pins specified in the following table. The strapping
option of MODE pins are latched on the rising edge of reset to set the default value of various registers. The values can be
modified by writing into the registers.
Default Register Bit Values
Mode FDX Mode Definition Register 0h Register 4h Register 1fh
(Note 1) (Note 2)
Bit [8,10,12,16] Bit [5,6,7,8] Bit 5
1 0 0 Force 10BaseT Half-Duplex. No Auto-Negotiation. 0 0 0 0 1 0 0 0 0
1 0 1 Force 10BaseT Full-Duplex. No Auto-Negotiation. 1 0 0 0 1 1 0 0 0
0 1 0 Force 100BaseTX Half-Duplex. No Auto-Negotiation. 0 0 0 1 0 0 1 0 0
0 1 1 Force 100BaseTX Full-Duplex. No Auto-Negotiation. 1 0 0 1 0 0 1 1 0
Z 1 * 100 BaseTX Half & Full-Duplex Advertised * 0 1 1 0 0 1 1 0
via Auto-Negotiation.
Z 0 * 10 BaseT Half & Full-Duplex Advertised * 0 1 0 1 1 0 0 0
via Auto-Negotiation.
1 1 * Isolated MII and TXP/TXM * 1 0 1 0 0 0 0 1
0 0 * All Capable Auto-Negotiation Enabled * 0 1 0 1 1 1 1 0
Table 1. Mode Selection
Note 1. Z indicates that input is floating.
Note 2. * indicates that values are controlled by FDX.
