Introduction The DS21458 is a four-port T1 / E1 / J1 single-chip transceiver (SCT) with the same register set as the DS2155 single-port T1 / E1 / J1 SCT. The DS2155 and DS21458 have the same software architecture, so it is easier to migrate from the single-port DS2155 to the four-port DS21458. This article details the subtle differences between the DS2155 and DS21458. The register image DS21458 contains four copies of the DS2155 register image, one for each port. Port selection is performed through the two high-order address lines A8 and A9. Although the memory images are basically the same, there are some small differences between the DS2155 and DS21458. Table 1 below summarizes these differences.
Table 1. Register image differences
| Register Name.Bit | Address | Bit Name | DS2155 | DS21458 | Comments |
| CCR1.3 | 70h | DICAI | X | - | Disable Idle Code Auto Increment-Selects / deselects the auto-increment feature for the transmit and receive idle code array address register, this funcTIon is not available in the DS21458 |
| CCR1.7 | 70h | MCLKS | X | - | MCLK Select, allows the user to select either TSYSCLK or MCLK as the master clock, this funcTIon is not available in the DS21458 |
| CCR3.6 | 72h | INTDIS | X | - | Interrupt Disable, allows the user to disable all interrupts regardless of the Interrupt Mask Register setTIngs, this funcTIon is not available in the DS21458. |
| CCR3.7 | 72h | TMSS | X | - | Transmit Multi-frame Sync Source, allows the users to select the framer or TSYNC pin as the source of the multi-frame sync, this feature is not available on the DS21458. |
| LBCR.7 | 4Ah | LTS | - | X | LIUC / TPD Pin Function Select, this pin selects the function of the LIUC / TPD pin and should always be set to a 1 in the DS21458. This bit does not exist in the DS2155 memory map. |
| PSA1 | F1h | - | - | X | Pulse Shape Adjustment Register 1-Allows the user to adjust the transmit pulse waveform, this register is not available on the DS2155. |
| PSA2 | F2h | - | - | X | Pulse Shape Adjustment Register 2-Allows the user to adjust the transmit pulse waveform, this register is not available on the DS2155. |
| IDR | 0Fh | - | X | X | Device Identification Register-This read only register displays the Device ID and Chip Revision of the given device and the contents will depend on which part or revision is used. |
Pin changes The pin names of the DS21458 are almost the same as the corresponding pins of the DS2155. One significant difference is that some pins of the DS21458 have changed to distinguish different ports. For example, the single RSIG pin on the DS2155 becomes RSIG1, RSIG2, RSIG3, and RSIG4 on the DS21458, corresponding to the four ports.
DS2155 has one MCLK pin, while DS21458 has two MCLK pins, called MCLK1 and MCLK2, respectively. These two pins can be driven by a common source on the DS21458.
The DS2155 has an XTALD pin, allowing the option to use a quartz crystal to connect to the MCLK and XTALD pins. DS21458 does not support this function, so there is no XTALD pin.
The 8xCLK pin is also not available in the DS21458. This pin is an 8-fold clock output of the DS2155, which was canceled on the DS21458.
The DS21458 has two additional address pins, A8 and A9, not on the DS2155. These address pins are used to select one of the four ports.
The DS2155 has four common user output pins, which no longer appear on the DS21458. These pins are UOP0, UOP1, UOP2 and UOP3.
The LIUC pin is used to separate the line interface unit (LIU) and the framer on the DS2155, and is called the Transmit Power Down (TPD) pin on the DS21458. On the DS21458, users have limited access to the clock and data signals between the framer and LIU, and the LIUC pin is no longer required. On the DS2155, the TPD function can only be used through the TPD bit in the LIC1 register. Due to limited access to the signals between LIU and the framer, the following pins no longer appear on the DS21458: TPOSI, TNEGI, TCLKI, RPOSI, RNEGI and RCLKI.
ESIB function The Extended System Information Bus (ESIB) function of the DS2155 allows up to 8 independent DS2155s as a group, sharing the same 8-bit CPU bus to report alarm and interrupt status. For this reason, in the DS2155 architecture, these signals of multiple devices are connected together externally. In the DS21458, the ESIB signal is internally converged, and only a single set of signals is drawn to connect another DS21458 to the ESIB bus to form an 8-port bus. For more information about ESIB bus functions, please refer to the DS21458 data sheet. JTAG function All four ports of the DS21458 use only a single JTAG chain. In the DS2155, there is only one port on the JTAG chain. For more information about the JTAG chain, please refer to the JTAG section in the DS21458 data sheet.Fully Automatic Washing Machine can make your clothes more clean in a very convenient way. With PCB control, different procedures can choose more ways to wash different clothes. Nowadays fully automatic washing machines are widely used in home, hotels and laundry shops.
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