Reading and writing TMC2300 registers

Firmware has implemented functionality to read and write individual Trinamic TMC2300 registers over internal UART single wire interface. It shares transmit and receive line like an RS485 based interface. Data transmission is secured using a cyclic redundancy check and each TMC2300 driver is addressed individually as follows:

Axis Address
X 0
Y 1
Z 2
A 3

Official TMC2300 documentation

All numbers in g-code arguments are decimal base numbers

Write registers

Write register command forwards g-command arguments to TMC2300 configuration interface. While it is not recommended because of stability issues, write command can be sent even if motors are turning (G0, G1, ... commands)

7'th bit of TMC2300 register has to be set to 1, thus for example 0x10 IHOLD_IRUN becomes 0x90

G100 P<xx> L<xx> N<xx> S<xx> F<xx> R<xx>
G-command TMC2300 address TMC2300 register (mask with 0x80) DATA3 DATA2 DATA1 DATA0

tmc2300_write2.png

Required checksum is calculated in firmware

Read registers

Read registers command has two arguments TMC2300 address and register address. It responds to terminal immediately.

G101 P<xx> R<xx>
G-command TMC2300 address TMC2300 register

Response is decimal coded 12 bytes. Sample reply looks like this: [TMC:5,0,16,112,5,255,16,0,0,0,0,157]

Reply byte Meaning
0 Echo transmit byte0
1 Echo transmit byte0
2 Echo transmit byte0
3 Echo transmit byte0
4 Reply from TMC2300 sync (0x05)
5 Address
6 Register
7 Data byte3
8 Data byte2
9 Data byte1
10 Data byte0
11 Checksum

tmc2300_read2.png

Examples

Set motor X current

Each motor driver can drive different motor. Power and other settings can be set individually. For example IHOLD_IRUN (0x10) register controls motor idle, run and timing parameters.

G100 P0 L144 N0 S0 F10 R5

G100 Write to TMC2300 g-command
P0 Driver address = 0 (X axis)
L144

TMC2300 register IHOLD_IRUN (0x10)

0x10 ->(set 7'th bit to 1)-> 0x90 = 144 (dec)

N0 Data3 = 0 (not used)
S0 Data2 = 0 (see IHOLDDELAY in table below)

F10

Data1 = 10 (see IRUN in table below)
R5 Data0 = 5 (see IHOLD in table below)

tmc2300_pwr_registers2.png

Read input register

Each TMC2300 driver has input status registers GSTAT (0x01) indicating over temperature, short circuit, and more.

G101 P0 R1

Response looks like:

[TMC:5,0,1,193,5,255,1,0,0,0,1,154]

Response contains only 3 bits of useful information. See explanation in table below.

tmc2300_status.png