AN2262 Motorola / Freescale Semiconductor, AN2262 Datasheet - Page 7

• Manufacturer Part Number: AN2262
• Description: Wireless HC08 Modem
• Manufacturer: Motorola / Freescale Semiconductor

User RS232 Ports
MOTOROLA
A buzzer with amplifier circuitry (C22, C25, R23, R26, R27, and Q1) (also found
on the original NET.08 board) is connected to the PTD4/T1CH0 pin. This dual
function pin (beside its normal I/O function) is shared with a 16-bit timer module
input/output. Here, in pulse-wide modulation (PWM) mode, it is used for tone
generation.
Some of remaining port pins are used for controlling the MC33491 and
MC33591/3 RF chips.
SPI module pins (PTD0/SS, PTD1/MISO, PTD2/MOSI, and PTD3/SPCLK)
plus two generic I/O pins (PTA5 and PTB4) interface with the MC33591/3. The
SPI implementation is described in detail in
Correspondingly, two pins which are employed by the 16-bit timer module
(PTD5/T1CH1 and PTD6/T2CH0) are used to drive the MC33491 transmitter.
See
an effective usage of the 16-bit timer module (TIM) for data stream generation.
Resistors R1 and R3 lower the 5-volt voltage to the levels required by
MC33491. One of the signals also serves as an antenna switch control.
(See also
A provision is made on the PCB so that the user can select either the RS232
or the RS485 serial interface. For simplicity, the selection is not made by
jumper or another similar method, but by assembling the relevant interface
chips.
The user RS232 serial port consists of:
•
•
•
•
•
16-Bit Timer (TIM) Operation in Manchester Mode
A level shifter, U6
Required capacitors C27, C28, C29, C30, and C37
A JP5 jumper with the 2-3 position closed
The JP6 (DSR2DTR) jumper could be closed providing simple status
information for the device that is connected on the remote side of serial
line. By connecting the DSR and DTR lines, a remote device may detect
whether or not the RF-08 board is connected. Refer to
Table 2
The paired signals RTS and CTS provide information about whether the
remote device is temporarily unable to receive data. If a serial
communication uses these signals, it’s called “hardware handshake” or
“hardware flow control”.
MC33491 to MC33493 Migration Notes on page
for a detailed explanation of all serial signals.
Wireless HC08 Modem
SPI Communication
which also describes
36.)
Table 1
Hardware Platform
and
AN2262/D
7