| Abstract: In this paper, the core microprocessor | | | | the SNI interface; 48 cited pin LQFP package |
| LPC2368, DP83848C Ethernet physical layer | | | | (7x7mm). DP83848C as an Ethernet physical layer |
| interface for the Chip , Detailed description of the | | | | transceiver, widely used in high-end peripherals, |
| embedded Ethernet interface implementation | | | | industrial control and factory automation, |
| method. First microprocessor LPC2368 and | | | | general-purpose embedded applications [2]. 3 |
| physical layer chip DP83848C briefly introduced, | | | | Hardware design 3.1 Circuit Diagram LPC2368 |
| and then given based on LPC2368 for Ethernet | | | | connected with DP83848C relatively simple, can |
| interface hardware design, the paper described | | | | be directly through the RMII interface. After |
| the software implementation process. 1 | | | | connected, DP83848C then the network Isolation |
| Introduction With the rapid development of | | | | Transformer And RJ45 interface access |
| Internet technology, people demand information | | | | transmission medium, the circuit diagram shown in |
| sharing is also rising. Currently, embedded | | | | Figure 1. 3.2 Ethernet interface design of the |
| systems have penetrated into every corner of | | | | actual circuit schematic DP83848C supports |
| our lives, it is the perfect combination with the | | | | several MAC Interface: (1) MII; (2) RMII |
| network for sharing information we provide a | | | | (ReducedMII); (3) 10 Mb Serial network interface |
| great convenience. PHILIPS is a good company | | | | (Serial NetworkInterface, SNI). Here we use the |
| LPC2368 microprocessors, embedded systems | | | | RMII interface mode, by setting the pin pin39, and |
| based on its Ethernet interface, if not, then the | | | | pin6 to determine, as shown in Table 1. Table 1 |
| application will also greatly reduced. Thus, the | | | | : MII Mode Selection MII_MODE (pin39) |
| entire system, the Ethernet interface circuit | | | | SNI_MODE (pin6) MAC Interface Mode 0 0 or 1 |
| should be indispensable, but it is also relatively | | | | MII Mode 1 0 RMII Mode 1 1 10 Mb SNI Mode Can |
| complex. Ethernet interface circuit mainly from | | | | be seen from Table 1, pin39 should be connected |
| the MAC controller and physical layer interface | | | | to the high, pin6 should be connected to the low. |
| (PhysicalLayer, PHY), two major parts. LPC2368 | | | | At the same time because the chip pin6 |
| embedded in an Ethernet controller, support the | | | | drop-down, the default is 0, so long as you can |
| streamlining of the Media Independent Interface | | | | set the pin39 connected to the high level, so that |
| (ReducedMedia Independent Interface, RMII) and | | | | the microprocessor LPC2368 can DP83848C with |
| with buffer DMA Interface (Buffered | | | | PHY chip connected via RMII interfaces. Between |
| DMAInterface, BDI), in half-duplex and full duplex | | | | them through the RMII interface, chip and |
| mode, providing 10M/100Mbps of Ethernet access. | | | | controller pins used to connect the number of |
| Therefore, LPC2368 internal fact already includes | | | | relatively small, and the data transfer rate is |
| Ethernet MAC control, but did not provide a | | | | every two, or frequency of 50MHz, it requires a |
| physical layer interface, therefore, need to add an | | | | 50MHz crystal oscillator connected to the pin34X1 |
| Ethernet physical layer chip to provide the access | | | | feet. In RMII mode, the main use to the pin: 1 |
| channel. Here's DP83848C use | | | | Serial Management: MDC (pin31), MDIO (pin30); |
| NationalSemiconductor as Ethernet physical layer | | | | 2MAC data: TX_EN (pin2), TXD [1:0] (pin4pin3), |
| interface chip, which provides, including MII / RMII | | | | RX_ER (pin41), CRS_DV (pin40), RXD [1:0] |
| SNI interface can be easily connected with the | | | | (pin44pin43); 3 Clock: X1 (pin34, RMII reference |
| LPC2368. 2 LPC2368 And DP83848C | | | | clock is 50MHz), X2 (pin33). Pin27 home made |
| Introduction 2.1 microprocessor LPC2368 LPC2368 | | | | DP83848C to 100Mbps high rate of work, LED |
| ARM7TDMI-S core based 32-bit micro-controller | | | | Show DP83848C working condition. 16ST8515 for |
| can operate up to 72MHz frequency, its powerful | | | | network isolation transformer, the main is a signal |
| and cost-efficient support 10/100Ethernet, full | | | | transmission, impedance matching, wave repair, |
| speed (12Mbps) USB 2.0 and CAN2.0B; chip with | | | | clutter suppression and the role of high-voltage |
| up to 512KB Flash, 58KB of SRAM, 10 A / D and | | | | isolation to protect the security of the system. |
| D / A converter and an IRC Oscillator , Also with | | | | By protel99 SE draw circuit diagram shown in |
| a SD memory card interfaces are available, | | | | Figure 2. Software to achieve three main parts: |
| 100-pin LQFP package (14 × 14 × 1.4mm). | | | | the system initialization, the data sent and |
| Widely used in industrial control, POS systems, | | | | received. Initialization part of the Ethernet |
| protocol conversion, encryption and other fields | | | | interface in use before the completion of the |
| [1]. 2.2 physical layer chip DP83848C DP83848C a | | | | initialization work, including provision of the relevant |
| 10/100Mb/s single-ended low-power physical layer | | | | register, allocation and initialization to send and |
| devices, there are several intelligent power-down | | | | receive buffers. Network interface layer in the |
| mode, including a 25MHz clock output, it is easy to | | | | corresponding data packet is a complete Ethernet |
| twisted pair media via an external transformer | | | | frame format, and therefore the sending and |
| and interfaces; supports two IEEE802.3u MII and | | | | receiving of data must be carried out in |
| RMII Rev1.2, convenient design; integrated | | | | accordance with Ethernet IEEE802.3 protocol, the |
| sub-layer supports 10BASE-T and 100BASE-TX | | | | protocol frame structure as defined by Table 2. |
| Ethernet protocol; low power consumption less | | | | Each card in the factory when there is a global |
| than 270mW, 3.3VMAC interface; can configure | | | | fixed physical address (MAC address). |