71M6521FE-IM Maxim Integrated Products, 71M6521FE-IM Datasheet - Page 23

• Manufacturer Part Number: 71M6521FE-IM
• Description: Current & Power Monitors & Regulators Residential Energy Meter IC
• Manufacturer: Maxim Integrated Products

Specifications of 71M6521FE-IM

• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 783-71M6521FE-IM/F, 783-71M6521FE-IMR, 783-71M6521FE-IMR/F 783-71M6521FEIM-DB,

The UARTs are dedicated 2-wire serial interfaces, which can communicate with an external host processor at up to 38,400
bits/s (with MPU clock = 1.2288MHz). The operation of each pin is as follows:
RX: Serial input data are applied at this pin. Conforming to RS-232 standard, the bytes are input LSB first.
TX: This pin is used to output the serial data. The bytes are output LSB first.
The 71M6521DE/FE has several UART-related registers for the control and buffering of serial data. All UART transfers are
programmable for parity enable, parity, 2 stop bits/1 stop bit and XON/XOFF options for variable communication baud rates
from 300 to 38400 bps. Table 13 shows how the baud rates are calculated. Table 14 shows the selectable UART operation
modes.
Note: S0REL and S1REL are 10-bit values derived by combining bits from the respective timer reload registers. SMOD is the SMOD bit in the
SFR PCON. TH1 is the high byte of timer 1.
Mode 0
Mode 1
Mode 2
Mode 3
handshake signals for inter-processor communication in multi-processor systems.
Serial Interface 0 Control Register (S0CON).
The function of the UART0 depends on the setting of the Serial Port Control Register S0CON.
Serial Interface 1 Control Register (S1CON).
The function of the serial port depends on the setting of the Serial Port Control Register S1CON.
v1.0
Parity of serial data is available through the P flag of the accumulator. Seven-bit serial modes with parity, such as
those used by the FLAG protocol, can be simulated by setting and reading bit 7 of 8-bit output data. Seven-bit serial
modes without parity can be simulated by setting bit 7 to a constant 1. 8-bit serial modes with parity can be simulated
by setting and reading the 9
SFRs for transmit and RB81 (S1CON.2) for receive operations. SM20 (S0CON.5) and SM21 (S1CON.5) can be used as
UART 0
UART 1
MSB
rate (internal baud rate generator or timer 1)
Start bit, 8 data bits, parity, stop bit, variable
Start bit, 8 data bits, stop bit, variable baud
SM0
baud rate (internal baud rate generator or
Start bit, 8 data bits, parity, stop bit, fixed
baud rate 1/32 or 1/64 of f
2
smod
SM1
* f
CKMPU
UART 0
timer 1)
Using Timer 1
N/A
th
SM20
bit, using the control bits TB80 (S0CON.3) and TB81 (S1CON.3) in the S0COn and S1CON
/ (384 * (256-TH1))
© 2005-2008 TERIDIAN Semiconductor Corporation
N/A
Table 13: Baud Rate Generation
Table 15: The S0CON Register
CKMPU
REN0
Table 14: UART Modes
TB80
Start bit, 8 data bits, parity, stop bit, variable baud
Start bit, 8 data bits, stop bit, variable baud rate
Using Internal Baud Rate Generator
71M6521DE/71M6521FE
2
RB80
smod
rate (internal baud rate generator)
f
CKMPU
(internal baud rate generator)
* f
CKMPU
/(32 * (2
TI0
/(64 * (2
UART 1
Energy Meter IC
10
N/A
N/A
-S1REL))
10
-S0REL))
RI0
LSB
DATASHEET
JANUARY 2008
Page: 23 of 101