HiRel/CanSat/Slave Sensors

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Type CanSat Slave Sensor Schematic Description
V1.0 200px|CanSat Slave Sensor V1.0 CanSat Slave Sensor v1.0 Schematic PDF


The sensors board comprises:

Mixed-Signal I/O

The analog inputs are digitized with the help of a 20-Port Programmable Mixed-Signal I/O MAX11300. The board pinout is compatible with the one of the MAX11300 evaluation board.


The MAX11300 I/O ports connections are provided in the following table:

Port Signal dir
0 3.3 V in
1 5 V in
3 humidity in
5 temperatire in
7 pressure in
9 LED 0 out
11 LED 1 out
13 LED 2 out
15 button 0 in
17 button 1 in
19 button 2 in

The buttons close a circuit to the ground. The other 9 ports are routed to connector J2.

The digital power supply is 3.3 V. the analog supply is 5 V.


The basic SPI frame uses 24 bits:

  • 7 address bits
  • 1 read/write bit
  • 16 data bits

The chip supports a burt mode where the basic frame can be enlarged by multiples of 16 bits.


There is one configuration register for each of the 19 I/O port. The configuration registers are found at addresses 20h to 33h. They are complemented by a DAC value each, at addresses 60h to 73h. These DAC values can be used to set the logic levels.

The 4 configuration register MSBs define the functionality of the port. Here some possible values:

  • 0 : high impedance
  • 1 : Digital input with programmable threshold
  • 3 : digital output with DAC-controlled level
  • 7: analog input to single-ended ADC

The configuration register LSBs provide parameters.


ADC ports, registers 20h, 21h, 23h, 25h and 27h, are configured with value 7100h.

Digital outputs

Digital output ports, registers 29h, 2Bh and 2Dh, are configured with value 3000h.

The output level is set by a DAC: for 3.3 V, registers 69h, 6Bh and 6Dh are configured with value 0547h.

Digital inputs

Digital input ports, registers 2Fh, 31h and 33h, are configured with value 1000h.

The trigger level is set by a DAC: for 1.5 V, registers 6Fh, 71h and 73h are configured with value 0999h.

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