Difference between revisions of "ER-301/Teletype Connection Rev7"
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The first few runs of the ER-301 did not have a dedicated i2c header. Instead users would perform a small hardware modification (described here) so that they could use the exposed UART header instead. | The first few runs of the ER-301 did not have a dedicated i2c header. Instead users would perform a small hardware modification (described here) so that they could use the exposed UART header instead. | ||
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| + | == Connecting the Teletype to the ER-301 == | ||
| + | |||
| + | In a nutshell, i2c requires 2 communication lines (SCL and SDA) plus 1 ground line. So there are 3 pins on the Teletype that need to be connected with a custom cable to 3 pins on the ER-301. | ||
| + | |||
| + | {{Pitfall|Since these connection pins were originally meant for UART communication you will need to perform a simple hardware modification to your ER-301 in order to enable i2c communication. Please refer to the '''I2C Mod''' section below for further instructions.}} | ||
| + | |||
| + | https://forum.orthogonaldevices.com/uploads/default/optimized/2X/6/62dc38713e6ee15dd27eac9679903d5763a9daff_1_690x353.jpg | ||
| + | |||
| + | There are 5 pins extending parallel from underneath the ER-301 CPU board. You will only be using the top 3. You can also see that the 5 pins are labeled on the ER-301 silkscreen as TX, RX, GND, GND, and 5V. Connect like this: | ||
| + | |||
| + | * Teletype GND to ER-301 GND. | ||
| + | * Teletype SCL to ER-301 TX. | ||
| + | * Teletype SDA to ER-301 RX. | ||
| + | |||
| + | https://forum.orthogonaldevices.com/uploads/default/optimized/2X/c/c50a2c0039157e49037072b19fb9e0bf22bf7ab4_1_690x428.jpg | ||
| + | |||
| + | == Required Hardware Modification == | ||
{{Pitfall|If your ER-301 board revision is revision 10 or later then this modification is NOT necessary.}} | {{Pitfall|If your ER-301 board revision is revision 10 or later then this modification is NOT necessary.}} | ||
Revision as of 21:06, 6 July 2018
The first few runs of the ER-301 did not have a dedicated i2c header. Instead users would perform a small hardware modification (described here) so that they could use the exposed UART header instead.
Connecting the Teletype to the ER-301
In a nutshell, i2c requires 2 communication lines (SCL and SDA) plus 1 ground line. So there are 3 pins on the Teletype that need to be connected with a custom cable to 3 pins on the ER-301.
 |
Since these connection pins were originally meant for UART communication you will need to perform a simple hardware modification to your ER-301 in order to enable i2c communication. Please refer to the I2C Mod section below for further instructions. |
There are 5 pins extending parallel from underneath the ER-301 CPU board. You will only be using the top 3. You can also see that the 5 pins are labeled on the ER-301 silkscreen as TX, RX, GND, GND, and 5V. Connect like this:
- Teletype GND to ER-301 GND.
- Teletype SCL to ER-301 TX.
- Teletype SDA to ER-301 RX.
Required Hardware Modification
| |
If your ER-301 board revision is revision 10 or later then this modification is NOT necessary. |
The goal of this hardware modification is to short out the diode labeled D3 on the red CPU board on the back of the ER-301. The diode's original purpose was to provide level-shifting for the RX pin of the UART port. Shorting out this diode allows for this pin to be used for the SCL (clock) pin of i2c.
 |
It is not necessary to remove the CPU board in order to perform this modification. |
Required tools:
- Soldering iron (ESD-safe, reliable temperature control) and solder (recommend no-clean flux)
- Short length of solid core wire (or waste lead from a through-hole resistor or LED or similar)
- needle-nose pliers (optional)
Step 1: Cut a 7mm piece of solid core wire or use part of a lead from a resistor or LED:
Step 2: Bend it around some needle-nose pliers:
Step 3: You should have a nice boxy U-shape like this:
Step 4: Place around diode D3 like this with the bottom of the U oriented towards the bottom of the board so that we do not short resistor R62:
Step 5: And solder like this:
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Do not use a solder sucker on this board. If you need to remove excess solder, please use copper braid. |
