MAX3111EEVKIT+ Maxim Integrated, MAX3111EEVKIT+ Datasheet - Page 6

• Manufacturer Part Number: MAX3111EEVKIT+
• Description: UART Interface IC Evaluation Kit for the MAX3111E
• Manufacturer: Maxim Integrated

Specifications of MAX3111EEVKIT+

• Number Of Channels: 2
• Data Rate: 250 Kbps
• Supply Voltage - Max: 3.6 V
• Supply Voltage - Min: 3 V
• Supply Current: 1.4 mA

The data communication between the EV kit and the PC
only requires TX and RX lines.
The logic of the RTS line (U1, pin 12) on the EV kit is
controlled by the MAX3111E’s RTS configuration bit.
RTS = 1 sets the RTS line to logic 0. RTS = 0 sets the
RTS line to logic 1. The logic of the CTS line (U1, pin
11) on the EV kit is controlled by the PC’s hardware
flow control (MAX3111E’s CTS = 0, D3 = On.
MAX3111E’s CTS = 1, D3 = Off).
Bits B3–B0 in the MAX3111E write-configuration register
determine the baud-rate divisor (BRD), which divides
the X1 oscillator frequency. The MAX3111E internal
oscillator operates with either a 1.8432MHz or a
3.6864MHz crystal, or is driven at X1 with a 45% to 55%
duty-cycle square wave. The MAX3111E IC data sheet
shows baud-rate divisors for given input codes, as well
as the baud rate for 1.8432MHz and 3.684MHz crystals.
The generator’s clock is 16 times the baud rate.
On the EV kit board, a 3.684MHz crystal is installed. A
user can replace it with a 1.8432MHz crystal or remove
Y1 and apply an external square wave on the EXTERNAL
CLOCK pad.
A user should first set B3–B0 bits to the desired values
on SW6 and then press and release SW1 to configure
the MAX3111E baud-rate divisor.
MAX3111E Evaluation Kit
Figure 3. MAX3111E EV Kit J1 Female DB9 Connector Pin Functions
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MAX3111E Baud-Rate Generation
Press SW4 on the EV kit to reset the µC and the
MAX3111E to its initial power-on-reset (POR) state.
See Tables 1, 2, and 3 for a description of the EV kit
jumpers and switch settings.
Disconnect the RS-232 serial cable from the EV kit.
Place the shunts of JU1 and JU2 in the 1-2 position; set
all other jumpers in their default positions. Press SW2 to
send single-byte 0x05 on the TX line. The byte gets
transmitted out of the MAX3111E’s transmitter line and
loops back to the MAX3111E’s receiver line. The µC
receives this byte from the MAX3111E and displays it
on the 7-segment LED.
Press SW3 to send single-byte 0x06 on the TX line. The
byte gets transmitted out of the MAX3111E’s transmitter
line and loops back to the MAX3111E’s receiver line.
The µC receives this byte from the MAX3111E and dis-
plays it on the 7-segment LED.
During the RS-232 loopback test, the RTS line is looped
back to the CTS line.
Jumper and Switch Settings
RS-232 Loopback Test
Hardware Reset