Freescale Semiconductor
Application Note

Document Number:AN4554
Rev. 0, 7/2012

Interfacing MC33903/4/5 With
MC9S08DZ60
by:Nitin Gupta
Automotive and Industrial Solutions Group

Contents

1 Introduction

1

Introduction................................................................1

System Basis Chip (SBC) combines several popular functions
typically used in automotive microcontroller unit (MCU)
based systems and utilize Freescale’s SMARTMOS
technology.

2

Hardware interface description.................................2

3

Software interface description...................................6

The SBC devices contain a combination of low-dropout(LDO) voltage regulator(s), switching voltage regulator(s),high-side switches, and one or more physical layertransceivers such as CAN, LIN, and PSI5. These devices arecontrolled by an MCU through a SPI interface. The prominent
features of SBCs include:• Can operate in various power-saving modes such as
Standby, Sleep, and Stop
• Configurable wake-up sources• In-built voltage regulator• One or more high-side switches• Configurable watchdog timer• Overcurrent detection• Undervoltage protection
The MC33903/4/5 is the second generation family of the
SBCs. It combines several features and enhances present
module designs. The device works as an advanced power
management unit for the MCU with additional integrated
circuits such as sensors and CAN transceivers. It has a built-in
enhanced high-speed CAN interface complying to theISO11898-2 and ISO1198-5 standards with local and bus
failure diagnostics, protection, and Fail-safe operation modes.
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3.1

Functional modes...........................................6

3.2

SPI commands................................................84

Conclusion.................................................................85

References.................................................................9

Hardware interface description

The SBCs may include up to two LIN 2.1 interfaces and up to four wake-up input pins that can also be configured as output
drivers for flexibility. The block diagram of the second generation SBC (SBC Gen2) family is shown in Figure 1.
MC33903 implements multiple Low-Power (LP) modes, with very low-current consumption. In addition, the device is a partof the family concept where pin-compatibility adds versatility to module design.
This application note describes how to interface MC33903 with the MC9S08DZ60. The same can be extended toMC33903/4/5 complete Gen2 family.

Figure 1. MC33903/4/5 block diagram

2 Hardware interface description
The MC33903 features one Voltage Regulator with power management, which can be either 5V or 3.3V compatible, CAN
transceiver (ISO11898-2 and 11898-5 compliant) with 5V-CAN regulator for CAN driver supply, configurable I/O withwake-up functionalities, watchdog capabilities and secured SPI interface for configuring the SBC. The internal block diagramof MC33903 is shown in Figure 2 with all the pin connections. The description of each pin is given in Table 1.

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Hardware interface description
VDD
regulator

VSUP1

VDD
RST

VSUP2

INT

VS2-INTSAFE

MOSIPower management
state machine

SPI

DBG

SCLK
MISO
CS

GND

Ocsillator

I/O-0

Configurable
input-output

CANH

VS2-INT
5V-CAN
regulator

5V-CAN

Enhancedhigh speed CAN
physical interface

SPLIT
CANL

TXD
RXD

Figure 2. MC33903 internal block diagram
Table 1. MC33903 pin definitions
Pin Number

Pin Name

Pin Function

Formal Name

Definition

3-4,11-13,
17-21, 31, 32

N/C

No connect

-

1

VSUP1

Power

Battery Voltage Supply 1 Supply input for the device internal
supplies, power on reset circuitry
and the VDD regulator.

2

VSUP2

Power

Battery Voltage Supply 2 Supply input for 5 V-CAN regulator,
VAUX regulator, I/O and LIN pins.

5

SAFE

OutputSafe Output (Active LOW) Output of the safe circuitry. The pin
is asserted LOW in case of a safe
condition is detected (e.g.: software
watchdog is not triggered, VDD low,
issue on the RESET pin, etc.). Opendrain structure.

6

5 V-CAN

Output

5V-CAN

Output voltage for the embedded
CAN interface. A capacitor must beconnected to this pin.

7

CANH

OutputCAN High

CAN high output

8

CANL

Output

CAN Low

CAN low output

9

GND-CAN

GroundGND-CANPower GND of the embedded CAN
interface

10

SPLIT

OutputSPLIT Output

Output pin for connection to the
middle point of the split CAN
termination

No connection

Table continues on the next page...

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Hardware interface description

Table 1. MC33903 pin definitions (continued)
Pin Number

Pin Name

Pin Function

Formal Name

Definition

15

IO-0

Input/Output

Input/Output 0

Configurable pin as an input or
output, for connection to external
circuitry (switched or small load).
The voltage level can be read by the
SPI and via the MUX output pin.
The input can be used as aprogrammable wake-up input in Low
Power mode. In low power, whenused as an output, the high side or
low side can be activated for acyclic sense function.

16

DBG

Input

Debug

Input to activate the Debug mode. In
Debug mode, no watchdog refreshis necessary. Outside of Debugmode, connection of a resistor
between DBG and GND allows theselection of Safe mode functionality.

22

RST

OutputReset Output (Active
LOW)

This is the device reset output
whose main function is to reset the
MCU. This pin has an internal pullup
to VDD. The reset input voltage isalso monitored in order to detect
external reset and safe conditions

23

INT

OutputInterrupt Output (Active
LOW)

This output is asserted low when an
enabled interrupt condition occurs.
This pin is a open drain structurewith an internal pullup resistor to
VDD.

24

CS

Input

Chip Select (Active LOW) Chip select pin for the SPI. When
the CS is low, the device isselected. In Low Power mode withVDD ON, a transition on CS is a
wake-up condition

25

SCLK

Input

Serial Data Clock

26

MOSI

Input

Master Out / Slave In

SPI data received by the device

27

MISO

OutputMaster In / Slave Out

SPI data sent to the MCU. When
theCS is high, MISO is highimpedance.

28

VDD

OutputVoltage Digital Drain

5.0 or 3.3 V output pin of the main
regulator for the Microcontroller
supply.

29

TXD

Input

Transmit Data

CAN bus transmit data input.
Internal pullup to VDD

30

RXD

OutputReceive Data

CAN bus receive data output

EXPAD

GND

GroundGroundClock input for the Serial Peripheral
Interface (SPI) of the device

GroundInterfacing MC33903 with an MC9S08DZ60 is very simple and easy. The application block diagram is shown in Figure 3.

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Hardware interface description
VBAT
D1
VSUP
22µF

VSUP1
100nF

5V-CAN>1.0µF
22k

I/O-0

100nF

VDD
>4.7µF

VSUP2
DBG

VBAT

VDD

RST

RST

INT

INT
MCU

MOSI
SCLK

SPI

MISO
CANH
60

CS
TXD

SPLIT

CAN

RXD

4.7nF
60

CAN BUS

VSUP

CANL
GND

SAFE

VSUP
OR
function

Safe circuitry

Figure 3. Application block diagram
Following is the description of MC33903 pins.
• VSUP1 is the input pin for the device internal supply and the VDD regulator. It is connected to the vehicle battery(VBAT) with surge protection using a Zener diode; this allows guaranteed reset free operation of the MC9S08DZ60
during the cranking pulse, and temporary (50 ms) loss of the VBAT supply.
• VDDis the output pin of the voltage regulator for the MC9S08DZ60. The maximum DC capability of the VDD is 150
mA1• RST pin is connected to the MC9S08DZ60, generally through a strong pullup, to provide a reset pulse under various
failure conditions, like, undervoltage at the VDD pin, failure in watchdog refresh operation.
• INT pin is the output of the SBC. It is asserted low or generates a low pulse when an interrupt condition occurs. Thispin has an internal pullup structure to VDD, as is the case with RST pin, but it is recommended to have an external
pullup.
• DBG is an input pin, and has a dual functionality. When voltage between 8.0–10.0 V is applied, it forces the SBC toenter Debug mode and when it is pull-GND through a resistor, Fail-safe mode operation may be selected depending on
the values of the resistor. See Table 2 for more details. Flexibility is provided to the user to select various modes
configurable through SPI commands, which will have a higher priority than the circuitry present at the DBG pin.

1.

This is the maximum current, when the device is in NORMAL mode.

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Software interface description• MC33903 has a CAN physical transceiver, whose inputs, TXD and RXD, are connected to the MC9S08DZ60’s CAN
interface, TXCAN and RXCAN respectively. CANH and CANL are the differential signals of the high-speed CAN
bus, compliant with ISO 11898-5.
• SBC can be configured using the SPI bus, which is the basic interface required to make it operational.

Table 2. Fail-safe options
Resistor at DBG pin

Safe mode code

Mode description

VDD status<6.0 kΩA

MCU remains powered, until
the failure condition isrecovered through S/W

15 kΩ

B1

Disables the MCU supply and Turn OFF 8.0 s after CAN
continues to monitor external traffic bus idle detection
event like CAN traffic

Remains ON

3 Software interface description
This section describes in detail, the software interface required for interfacing MC9S08DZ60.

3.1 Functional modes
MC33903 can be configured to operate in different modes by using the SPI commands. In order to understand the SBC, theuser must be well-versed with the different modes of SBC, which are summarized in Figure 4.

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Software interface description

Figure 4. State diagram
1. When the SBC is powered-up, it transitions to INIT RESET mode automatically, during which the RST pin is asserted
low for duration of typically 1.0 ms (T_IR). BATFAIL flag will be set to indicate the device is coming from anunpowered condition, and all previous device configurations will be lost.
2. After INIT RESET, the SBC automatically transitions to INIT mode, in which it must be configured through SPI,
within 256 ms (T_INIT), and a Watchdog (W/D) refresh command must be issued on MOSI, failing which SBC
transitions back to INIT RESET mode and if successful, it will transition to NORMAL mode.
W/D refresh command must be issued periodically by the MCU in NORMAL mode, within the specified time
(T_WDN), as was configured via SPI.
3. If the MCU does not issue the W/D refresh command, SBC will transition to RESET mode, in which the RST pin isasserted low, for duration of typically 1.0 ms (T_R), and will transition to NORMAL REQUEST mode. A W/D refreshInterfacing MC33903/4/5 With MC9S08DZ60, Rev. 0, 7/2012
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Conclusioncommand is necessary to transition to NORMAL mode from NORMAL REQUEST mode. The duration of the
NORMAL REQUEST mode is 256 ms (T_NR).
There are two low-power modes which can be entered on request by MCU, via SPI commands.
• LOW POWER VDD ON mode: As the name suggests, in this mode, the internal regulator will remain ON and will
supply 5.0 V to MCU, through its VDD pin.
• LOW POWER VDD OFF mode: In this mode, no power is supplied to the MCU.
In each of these modes, wake-up sources can be configured via SPI, and after receiving any one of the wake-ups, the SBC
will transition to the modes as shown in Figure 4.

3.2 SPI commands
For configuring the SBC, MC9S08DZ60 must read all the flags, using the SPI Read command, to check the source of thewake-up, reset or the interrupt, and then configure the corresponding register for wake-up (WU)/reset (RST)/interrupt (INT)
source(s) according to the requirement.
When the SBC status flags are read at power-up, they will show that INT/WU/RST source is from a regulator event. At thismoment, if VREG flags are read, by issuing 0xDF00 or 0xDF80 on MOSI, MISO will show that the VSUP_BATFAIL bit(bit 1 of the return status) is set, indicating that the SBC is coming out of the POWER DOWN mode. Wait for SBC totransition to INIT mode, 1.0 ms from the time the SBC is powered-up, and then configure INIT Registers, INIT Wdog, INIT
REG, INIT LIN I/O, and INIT MISC, as they can only be set when the SBC is in INIT mode. On MOSI, issue a command
0x5A00, W/D refresh command, so that SBC transitions from INIT mode to NORMAL mode.
NOTE
One must check the mode of the SBC by issuing 0xDD80 on MOSI and monitor the bits
7–3 on MISO as shown in Table 3,2 and if the mode is not INIT, then reissue thecommand 0x5A00, till SBC transitions to NORMAL mode and whole process must becompleted with 256 ms, otherwise the SBC will transition to INIT RESET mode.

Table 3. MISO bits 7–3 (SBC current mode)
b7

b6

b5

b4

b3

Mode

0

0

0

0

0

INIT

0

0

0

0

1

FLASH

0

0

0

1

0

NORMAL REQUEST

0

0

0

1

1

NORMAL mode

1

x

x

x

x

Low-Power mode

The user must configure the CAN, voltage regulator, and the Interrupt Source register as per the requirement of theapplication.

4 Conclusion
This application note has described the hardware and software aspects of interfacing the MC33903, SBC Gen2 with
MC9S08DZ60, and HCS08 CPU.

2. Please refer to MC33903_4_5, System Basis Chip Gen2 with High Speed CAN and
LIN Interface, available on http://www.freescale.com

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References

5 References

The following reference materials are available on http://www.freescale.com.
• S08D: 8-bit Cost-Effective with CAN D MCUs
• MC33903: System Basis Chip Gen2 with High-speed CAN and LIN Interfaces• MC33903_4_5 : MC33903_4_5, System Basis Chip Gen2 with High Speed CAN and LIN Interface• MC33903_4_5FS : MC33903_4_5FS, System Basis Chip Gen2 with High Speed CAN and LIN Interface• MC9S08DZ60 : MC9S08DZ60, MC9S08DZ48, MC9S08DZ32, MC9S08DZ16–Data SheetInterfacing MC33903/4/5 With MC9S08DZ60, Rev. 0, 7/2012
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Document Number: AN4554
Rev. 0, 7/2012

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