HighlightsA low-cost controller for variable-rate seeding was developed.The controller successfully identified management zones and changed the angular velocity of the seed metering device.The variable-rate controller maintained the actual seeding rate according to the prescribed seeding map.Abstract. The use of machines for variable-rate applications is becoming popular in modern agriculture. Due to the presence of imported and complex components, the acquisition cost of these machines is high for smallholder farmers. Several studies have been carried out using low-cost components in the development of precision agriculture machines to facilitate their adoption in low-income agriculture. Thus, the objective of this work was to develop a variable-rate controller for a low-cost precision planter. The system was developed and installed on a 1-row manual planter with a horizontal perforated disk distributor. A direct-current electric motor was used to drive the seed metering device. The angular velocity of the electric motor was controlled by a BeagleBone Black single-board computer. A program was written in Python 3.6 language, and a graphical user interface was generated by using PyQt5. Field trials were performed with maize seeds using a 28-hole disk and a prescription seeding map with four management zones. The row spacing was 0.75 m, and the planter ground speed was close to 1.0 m s-1. Field tests showed that the controller was effective at identifying the four management zones and controlling the angular velocity of the motor. By counting the number of plants germinated in the field test, it was verified that the variation in the angular velocity of the motor produced a change in the planting density. At each management zone, the planting density corresponded to the prescribed seeding map. The total cost of the parts used to assemble the controller was US$337.97, characterizing it as low cost. Successful field tests showed the potential for using low-cost components to develop variable-rate machines for smallholder farmers. Keywords: Low-income agriculture, Management zones, Precision agriculture, Single-board computer, Smallholder farmers.